Why do we push 8 in 4.1 / 4.2 ?

I started playing at the end of set 1 dan I've been playing on almost all sets. Maybe it's because I kept bad habits from when I was low elo but I don't remember a single time when everyone except reroll comps pushed lvl 8 in 4.1 and rolled all their (usualyy less than 30) golds to find their upgrades. What happened ?

I just watched a few videos from set 12 from Voltariux and he usually pushes in 4.5, he has 50 golds so he can roll for upgrades and still have a good econ.

Is it because we have more ressources from pve / encounters ? Or maybe we take more damage in stage 4 ? I also suspect that it's because elise is extremely contested because too useful, maybe the 3 cost are too weak at 2 star so it makes sense to skip them unless you play reroll.

I don't really understand this meta