It's because they try to sell their characters to everyone, not just nerds.
So they keep characters abilities balanced enough for regular people to enjoy it without facing
"battle scene fatigue" and balanced enough for nerds to enjoy it without being overly flashy.
Might as well stay home when that movies comes out because that infinity gauntlet is gonna be nerfed. That nikka Thanos was fighting Celestials with
planets, my dude
He was legitimately a God. Marvel can't sell the the current lineup of heros beating that type of power