I am trying to figure out why exactly bliz randomly decides that some classes should be AoE capped and other should not. The way M+ is played these days - we are doing virtually all large pulls. If you happen to play a class / spec that is AoE capped, you are simply not competitive dmg wise.
I am trying to figure out the point of capping some classes and not others. It feels like it massively hinders so many specs. Why do this?
You won’t get any definitive answer. All the announcements and dev discussions I recall didn’t contain any explanation, just the assurance that “this is the right answer because we decided it this way.”
Devs don’t answer “why” questions.
Some classes perform well on big pulls, some perform better on the low cleave pulls.
When you look at the damage meter based on over all damage at the end of a run instead of isolated pulls, it usually balances out.
Usually…
they literally said they want certain classes to excel at smaller pulls and others to do more on larger packs. some classes are also jsut busted when they are uncapped coughcough(rogue)coughcough. they also wanted larger pulls to feel more dangerous.
Shhh. Lies. 
There are very few uncapped aoe spells left in the game.
Destro is one of the best ones for uncapped aoe and they haven’t been meta all expansion.
Uncapped AoE tends to not hit that hard against just a few mobs. Demo’s Implosion is uncapped.
They do but it can hardly even be classified as a legitimate reason. At the end of DF S3 PTR cycle the Rogue dev was in Yodas stream for multiple hours and literally did not give a single answer as to why Outlaw was target capped other than “Because it’s interesting”.
https://i.imgur.com/PYaOlKs.png
Absolute joke.
Blizzard thought capping AOE damage would reign in M+ mass pulling behavior. That never worked. They’ve been slowly and haphazardly walking back that decision ever since. Efficiency will always push towards mass pulls and the bottleneck will always be damage intake. IF they were serious they would rebalance damage output of mobs away from group spam and crank up mob melee damage, to actually punish the tank for overpulling.
It’s to prevent homogeneity, and it never worked because they left some classes uncapped. Even the specs with specific low caps, such as Fury Warrior (primarily five targets) aren’t even the best cleave DPS at their own target caps.
it’s because every MDI team was double-DK.
I think for some specs it’s because of the way their aoe works. Usually there’s distance/ground targeted aoe that requires targets to be close, and then there’s cleave aoe that doesn’t.
Like a demo warlock is uncapped, however their aoe requires them to have their pet in range and the adds must be grouped together to get full effect.
Other specs like shadow or affliction only require the mobs to be grouped for their initial dot application (if using aoe applicators), after that their aoe is cleave damage rather than distance restricted aoe.
Once dots are applied the tank can move the mobs all over and the mobs will still be taking damage.
Can’t tell you how many times I’ve pressed implosion right as a tank moved the mobs and I lost so much damage
Tl;dr
MDI teams were running Fire Mage / DH / BM Hunter / Outlaw almost exclusively (especially after the changes that don’t allow class stacking) so Blizz hard capped all the AoE abilities from just about every class.
That felt awful, everyone complained about it, and they ended up reverting it back to where it is now - most classes have a soft-capped AoE (reduced damage beyond (x) targets), and some others have uncapped AoE.
I don’t think there’s any rhyme or reason to it, other than keeping the top teams from pulling the entire instance into a boss and having your “skill check” be how well your tank can mob control and your teams ability to follow a kick rotation.
Honestly I wouldn’t worry too much about the target cap. I personally don’t notice it on any of the classes I play.
Sub and sin are terrible in keys so rogues just like in season 1 are effectively banned from pugging Algethars because Outlaw is target capped. You can still dumpster the dungeon on overall but it doesn’t matter if you lose to the tree boss because the specs capped.
It absolutely matters.
this is a bold faced lie lmfao. BM hunters will pretty much out dmg you in >8 mob pulls, <6 mob pulls, AND in single target. so will demo locks and DHs
Then why did they hard cap shamans?
Yep, that’s Blizzards balance in a nutshell. Some uncapped AOE kills just as well if not better than capped specs. “Aoe” specs that do single target damage that’s like 90% of a single target spec but the single target specs AOE is 10% of the AOE spec. DPS specs with tons of utility topping the charts and DPS specs with no utility at the bottom. Tanks that outheal, outdps, and out mitigate others. Super complicated DPS specs that get out dpsed by dead simple DPS specs. Balance in WoW is just an absolute mess.
same “logic” as with outlaw rogues
Nerf rogues!
It’s starting to feel more than just intentional. Seems like they want most people playing the easy meta specs so they don’t have to fix the broken ones until next expansion. Specs that “hit everything with one ability” or “all my abilities hit everything” seem to get all the love, while the complicated ones couldn’t get pissed on if we were on fire.