Mostly due to agro dump. As in lets say you have a Fury on Condor and your entire team are tac-cloak spamming winfiltrators. That Fury is going to have a bad day.
I'm just saying as lately I've developed some sort of conscience and even without thinking it I've been avoiding the Infiltrator class more often. Just as I avoid Disrupter Ammo & Overload if a biotic is present (wish others would do that when I at least Fury, lol). Why should I have such an advantage over the pugs when I'm the one with more playtime & experience then most pugs I bump into?
But meh, it's just a thought. So wondering what others think...
You can mostly avoid that problem by presetting your map and/or enemy.
There's a lot of things I don't like in this MP, such as plenty of hazard maps (Ghost with screenshake if you're hosting and standing on the rain with shields, Dagger in general, White for making half the map pretty much unplayable, Giant with the beloved screenshake and **** visibility), huge and/or open maps if you're playing with a CQC kit and/or short range weapon, Geth enemies at any given time and place... let's not forget that any given map turns into a hazard at w11 because pugs will mindlessly rush into the LZ and inevitably get destroyed, but I digress.
2/3 of all my matches were on infiltrators and I honestly don't give a ****. Don't cry about the aggro dump, you have a shitton of cover in most places (running around in the open is generally a bad tactic in this game) and especially sniper infiltrators aren't drawing much aggro to begin with.