This has been demonstrated in a few competitive games this year, most notably Na'Vi vs. Darer in which Darer won through protecting Death Prophet, though in general the team fighting seemed to be largely in Na'Vi's control. In other games against Darer where Death Prophet was not picked, it was more or less completely one-sided for Na'Vi.
I know some people might think this is exaggerating, but I'd consider Death Prophet a first-round ban, in the same tier as Nature's Prophet and Leshrac. If she is protected, her team can easily force a loss just by fighting near towers and keeping Death Prophet up during her ultimate. That's it. Of course there's more execution involved but as for a general strategy that is incredibly easy and has very small risk compared to the potential reward.
I prophecise that this hero will become much more popular by the International. It will be interesting to see if any real hard counters can be found by then too.
I had a game the other night where the enemy team actually fed something like 56 kills to us, and only got 20 or 30 themselves, but we kept losing out our buildings faster than them because of the fact that DP's ult could tear that stuff down as long as we were just fighting her team on our turf. It was like no place on the map was safe with her ult going on--and since it lasts for such a duration and can't be countered by a BKB, it could effectively make a defense of your own barracks a lost cause just because her ult was present. So then you are forced to dive her and probably lose the fight because of her teammate's control/gank potential, or you win the team fight while her ult chews your base.
If you watch that footage of Na'Vi and Darer, you see a similar thing. Darer mostly focused on avoiding having hard losses in team fights so they could stay in to late game and bank on DP's ult burning the buildings down anyway.
http://www.joindota.com/en/news/3129-bulba-current-flavor-is-death-prophet
And I will say this: You make good points about the gank emphasis, the anti-farm/anti-push we see, but I think the reason we see these gank line-ups is because pushers aren't available after the ban phase. With heroes like Lesh, Chen and others being banned, Death Prophet could potentially domninate the currently developing meta and be added to the first-round ban list herself. Great discussing this with you man.
The team compositions have definitely shifted to include more strong early game heroes as far as can be seen in the most recent tournaments, pushers only being "minimal" in the line-ups because of how they're always banned. Other than that, I have no idea where you're getting this stuff about pushing being out of the metagame, or where you're seeing so many more carries. I will concede that the grand finals of the GB JD Masters tournament was more in line with what you were saying as far as carries go, but most of that tournament was push, push, push and early game heroes for sure. (Always with some exception to the Chinese teams however.)
Right now, teams are clearly trying to ban out the big pushers and avoid having to take on that sort of team composition. During the GB JD Masters tourney Anti-Mage got banned first much less, often enough not even in the first round. He almost always came behind the pushers. I think I even saw Death Prophet as the first ban in a game from that tournament as well. Lycanthrope, Leshrac and Nature's Prophet were banned almost every single game.
In any case, I'm not saying Death Prophet is necessarily better than Leshrac or whoever. I'm not saying she's a faster dpser than Leshrac or whoever. I'm just predicting, based on what we're seeing now which is a pretty good indication, that Death Prophet will be used more going into the International. She's simply another hero to add to the ban list, whose presence could be a lost game for one team, or her being banned could mean the presence of another hero like Leshrac or Nature's Prophet.
We really wouldn't see a Darer team full of stand-ins and an out-of-shape Artstyle beat Na'Vi just because they picked Death Prophet if there wasn't more to that hero than a spammable nuke. Her ultimate may take a while to get out, but she can't be countered by a BKB, she's way tankier than Leshrac, has great mobility, and can spam a silence, not just an aoe nuke. She is also incredibly durable once she has items. She's really not that weak, otherwise, again, we would not see top-tier teams like Na'Vi being beat by a hodge-podge of ex-M5 players, stand-ins and a rusty Artstyle with a line-up built around Death Prophet and counter-pushing (a team that otherwise had horrible losses for most of their other games). If she doesn't get smashed hard early, if a big tower advantage isn't carved out first, she can become a huge problem.
I think Snoopy answered fan questions and pointed out a lot of flaws with DP. Her teamight is very slow for one, besides a fairly spammable nuke, she can't accomplish much. Her ulti does a lot of damage, but over a LONG time. A team doesn't even need to protect her because she isn't a real priority in a fight. Other heroes (Lesh) output all her damage in half the time.
A good team can easily protect a Death Prophet pick just like they would a carry hero that needs protection early on. I've seen games where Ursa managed to absolutely crush the other team even though realistically Ursa is a garbage hero beyond low-skill pubs.
Death Prophet is only one of five heroes on a team and fits very well into any pushing strategy, and scales incredibly well for late game. Her only down side is the laning phase because of her lack of natural defense, as you pointed out. Beyond that though she's an insanely powerful hero. Once you can get some regen or tankiness on her, it's over, and we've definitely been witnessing that more and more lately in tournaments. Maybe a couple months ago you'd still be right, but I think at the moment we're seeing the metagame revolve more and more around heavy pushing teams.
I'm calling it right now, she will be picked and banned a lot more during the International.
Snip
Almost all heroes played in competitive games have a good form of escape or stun. Lesh has an AoE stun to stop a potential gank.
Many pros have gone over this better than I can, but basically, there isn't a good lane for her to go in and she is gank bait.
She's got a ranged autoattack, a silence, a good nuke and an insane ultimate at any rank. She's not that weak early game, a lot of heroes don't have any legitimate means of escape. That's where smart play comes in.
Leshrac for example has no way to escape and is even squishier than Death Prophet, but he wields heavy pushing power and damage, so he is still banned almost always in the first round because if protected, Leshrac's presence guarantees the loss of buildings if he is not taken out right away. And his stun has an obvious animation and large delay. Death Prophet has no such issues with any of her spells. I'll agree that Leshrac has a stronger early game, but that's why Death Prophet is scary: she scales wayyy better than Leshrac.
Death Prophet is the same sort of thing, but on a much stronger scale because of how potent she remains late game. She has a silence, good strength gain, great mobility, can spam her spells, and pushes insanely well with her Q and R. Either you have to go through her teammates while she destroys your buildings, or her teammates wipe you out because you tried to burst her down while she was being guarded.
That's a definite first-round ban and I think we'll see her chosen and banned more often leading into the International this coming August.