I tried the eternal queue for tiers 35+ and one common problem I experienced is that players just want to push their maximum tier, which is totally understandable.
Why lock the tier to the lowest rank in the group?
If the following players are in the group: 35,36,37,38
Just let us queue to eternal 38. This would completely eliminate the issue with players leaving because they want to push their tier. This will also remove some pointless grind, because there's no big difference in running eternal 35 or 38.
I've seen the issue is even worse at eternal 40+.
Players are usually bis or heavily geared at those levels, there's no reason to keep pushing tiers one by one. Just let people push the highest tier available for them, instead of forcing them to grind some tiers that they are going to beat anyway.
Some would say that this would encourage elo boost, but elo boost can already be done, but with extra steps. There's no point in punishing all the rest of the players.