I think there is a fundamental problem in these discussions where it is assumed the role of mentor should be an award, an indicator of progress, or something similar. This line of thinking isn't productive for the purpose of assisting new players.
There's nothing wrong with expecting mentors to put in effort for new players, because they have signed up for this idea not once, but twice.

Becoming certified as a mentor is one thing. Should you wish to take a break, you can hide your crown.
Signing up for Mentor Roulette means you have no excuse. If you have a crown in a duty, I expect you to be helpful to the sprouts and beware of potential wipes- something a mentor has never done when I have met them.