Beats me, because filling has absolutely nothing to do with mentoring.
At least two of us in this very thread have said that we don't care about the shinies. But the problem isn't that we don't want to help, it's that we don't want to waste energy with people who don't want to be helped. If a sprout tank is chain pulling Ramuh EX before we can explain any mechanic, or people don't even try to place the titan gaols correctly after 10 pulls, what are we supposed to do? Stay the entire lock out for absolutely nothing?Nobody forced anyone to sign up for the mentor program either though. I think a very large population of "mentors" or at least the ones who balk at finishing what they queued up for only saw the shinies and not the actual purpose. It is not a penalty to help others, it was the entire idea behind the program. If you don't wish to subject yourself to the possibilities, don't queue at all.
The mentor roulette has no reason to be and EX shouldn't be in it because of the nature of EX content. It's really weird to encourage sprouts to use DF for something that would have belonged in RF when they might not even understand the basics of their job yet.