Is Windranger really the highest damaging carry 6.83?

Desolator is not preferable compared to any proc-based item. If you replaced your desolator choice with an MKB, you would get so much more damage.

Windranger BAT = 1.5

Attacks per second = 1.5 / (1+600/100), 7.5 attacks per second.

average of 2.6 Monkey King Bar procs/second, which adds up to an average 262.5 minibash damage + 660 bonus damage per second.

MKB = +922.5 dps (assuming you have Aghanim's Scepter at lvl. 16, and you get minibash exactly 35% or the time)

Desolator adds 450 raw dps plus another 29.6% damage increase due to armor reduction. you end up with an added 582.2 dps

That's 340 more dps you get from an MKB, plus the added benefit of destroying any abilities with evasion. (That's why Windy is so effective in most pubs I play. Phantom assassin is picked 95% of games). You could argue that deso is better since it works on buildings and is 1300g cheaper, but if we're trying to find the real damage dealing item, MKB is the winner hands down.

Sources: Liquidpedia, Dota 2 wiki.