Disputing being placed in low priority?

Just had something similar. I'm new to this type of game - been playing DOTA2 for about a week now. I've just abandoned a game because some dude had a hissy fit at me for healing someone else. I was Omniknight - the guy I healed had more health but was fighting an enemy hero and I got a gank out of it (he'd have lost if I didn't use Purification). The guy complaining was almost dead, but well away from the fight. He them went on to declare that as the other three players on our team are his friends, I can expect 3 reports for intentional ability abuse. They then all huddled together at top, leaving me solo mid, and the other guy solo bottom. They would initiate team fights near us and then flee, leaving us to die. Basically, a bunch of morons.

I left after 18 minutes. It was just constant text grief (much of it racist). They weren't even any good - they managed to lose all three top towers by the fifteen minute mark against Zeus and Keeper of the Light. The other two of use had to deal with Drow, Huskar and Riki and were managing to hold mid and bottom between us.

Really not a great introduction to the game. I've got two days in low priority mode for doing the right thing, while they might get a day each for being abusive, racist and deliberately hampering the team. Feels like they got off easy while being the ones in the wrong, simply because there's more of them.