The problem is that very few good players would use it. It would be like the dungeon finder x5. As is, even on normal trials, manual pugs often fail. Just think how bad it would be when you have no wa
Considering how often I get group-finder groups with no competent DDs, I think any Trial formed this way will crash and burn, will just get rekt by casuals.
Do it for normal only. Or just don't go use the group finder yourself and all your problems will be non existent. Not a hard concept not to use something you don't like.