This is the problem we have when roulettes are forced upon players to progress MSQ (they should be removed from the MSQ in my opinion). Make dungeons and trials "optional" content that sets it apart from the "casual". SE needs to have some form of intro for the various levels of this content - maybe an idea for them to replace guildheists with something meaningful there.

POTD and similar does not help this situation - people learn very, very bad habits there that simply do not translate into real dungeon and trial content.

As for the Mentor system - yes it is by and large broken. That is not the fault of the mentors though - its the fault of SE for not bothering to expand upon Hall of the Novice when they should have. It should have been the go to place for intros to new levels of content - it should have been forced and not optional.