Just a bunch of reasons why tanks can’t push:
being forced to wait out and respect abilities (Mei wall, Bastion turret)
having to wait for the dps and supports who just died to a sniper
not getting healed and being unable to push in with half hp
dps and supports not being able to deal with flankers
ends the game faster when merely playing for a weekly challenge
too much damage in the choke to even walk through until dps (and supports) either flank or take an off-angle
Lifeweaver. His lifegrip specifically is by far the worst ability they added to this game. A bad lifeweaver (even if he means well) can get you killed in multiple ways or just throw fights entirely because of bad pulls.
That being said, there are a lot of heroes that are poorly designed right now such as Mercy, Hanzo, Illiari, … but their numbers can be tweaked in multiple ways for most part to balance things.
With lifegrip you can’t really do that as lifegrip’s problem isn’t the numbers, it’s how the ability works.
There’s 13 weekly challenges and you only need 12 for all rewards. Just leave that one out and do all others.
Dailies also have enough other options.