People like this are why I generally do roulettes as a Warrior. No matter how badly it goes, you can just do it yourself if the rest of the group fails. You're tanky enough to survive pretty much anything, and Holmgangs short cooldown will let you cheese some group mechanics and keep going. You can even solo max level raid content if you know what you're doing.
At this point in time I accept that people are going to screw up repeatedly. I usually expect nothing and I somehow still end up disapointed with people anyway. I have a very low opinion of other players.
Most people see Mentorship as either a means to get an extra XP bonuses or a way to reach a wider audience for trolling. It's a well intentioned system, but how people were going to use it doesn't seem to have been considered from the outset. I still think it's a good idea, but it really needs a rethink of the rewards that are attached to it.
I'd be all for making it a 1-to-1 system, where New players would get matched with an experienced player who's willing to show them the ropes rather than the extra roulette it is now. I feel like there's a lot of scope for improvement with the system as a whole. Even as an expansion to the Hall of the Novice and guildhests it's a good way to teach players mechanics in a potentially lower stress environment if nothing else.