Yes, this! FS has completely borked the balance, up to a point where you can’t properly balance anymore.
If you have a party of single target damage dealers (like GK, Shade, & BH) a bossfight or fight with a randomly spawned monster is over in seconds, even on Cata. I’ve seen Boddvar and Skarrik die before finishing their first sentence, and not all too rarely my monster lifetime registration mod shows me numbers under 20 seconds. If nobody brought a single target damage dealer, however, (say a party of IB, HM, FK, UC) the same fight can last dozens of minutes instead. This situation is completely unbalanceable. If you balance fights around the first party, they will become ridiculous for the latter. And when you balance it for the second party, they will become even more trivial for the first one.
It’s perfectly fine to have classes being better at one aspect of the game than others. And a specific party being better at a specific thing than another one is also perfectly fine. But the disparity right now is simply too big. You could accept that, and say in V2 taking your party composition in account should be a thing. You’d need to coordinate with your teammates and have characters to compensate each other’s weaknesses, right? I completely dislike that. Not only because of quickplay becoming more difficult, but also because it restricts choice and variety.
And even then the overall balance is still off, because a single target class can deal with its weaknesses (like hordes) relatively much better than a crowd control class can deal with monsters. This disbalance shifts the meta towards single target classes way too much.
So, how to solve this? I feel the only choice is to reduce the disparity in single target damage between classes. Easiest solution would be a damage cap vs. monsters and bosses (with a lower cap vs. bosses than vs. monsters) for the culpable skills like Infiltrate and Blessed Strike. Those skills could then still delete things like Chaos Warriors, but without making certain fights trivial and unbalanceable for when those skills aren’t in play.
A more creative option I would really like to see could be to do the above, but then also reduce monster hitpoints by a lot. That way, monsters still die really fast to single target specialists, but also a lot faster vs. classes that aren’t as dedicated. And when monsters are therefore easier overall, you could spawn them in a lot more per map! Think about it! Monsters can make situations a lot more interesting, their offensive qualities are still awesome, so fighting them is still fun, but the fights become a lot less damage-sponging slogs overall. And since monsters come more often and are still a threath, it’d still be a good choice to pick single target specialists. But not bringing one isn’t causing such a ridiculous disparity either.