I think it's pretty obvious the target cap is a bandaid fix to the current degenerate meta their design has created with tanks kiting huge packs of mobs around without losing threat or taking much damage due to the plethora of aoe snares and stuns available in class comps pushing for the limit of what's possible.
Nobody likes being limited because they can't come up with something better/let 1% of players dictate gamedesign and gameplay and call it a day.
As I see it, it all comes down to speed and that dumb clock they slapped into M+ even though it needn't be there if they just went back to the drawing board and came up with something original for once... or went back to just forcing tanks to take hits to keep aggro -.-
Feels pretty dumb as well when they just arbitrarily pick and choose which spec gets uncapped aoe for the tier and thus become fotm because of the fact. It's like one hand at blizz wants the other to look like a joke while the head claims balanced! to the players.