Um, I'm a mentor who didn't get the status through running dungeons. I love hanging out in the mentor channel and giving advice, and helping strangers whenever I'm in the cities and they see me standing around with a crown. I've met lots of cool newbies that way and my server is pretty dead so it helps me reach out and talk to new players. I would be sort of concerned if my status was stripped because I didn't offer deep insight into tank mechanics in a hard fight one day just because someone assumed I had got there via mentor roulette and wasn't doing 'my job' properly. Furthermore, many players don't speak the language everyone presumes is the dominant one (here, English). What if they're say, a Spanish player who can communicate fine to do their job but not to explain how to tank Shiva when they don't main tank in the first place? It's unfair and presumptuous to assume everyone else speaks your language fluently.

I agree that encouraging speedruns of mentor roulette for a reward was silly. There should be a popup warning screen saying 'you're joining this roulette as a mentor, so you should focus on helping with the clear' or something rather than tempting people to charge through the content for a mount reward they can show off. But I don't even join mentor roulettes because I'm not confident in knowing every combat job well enough to give advanced strategy pointers in a language which isn't my first, and I'd be upset if people thought that meant I couldn't mentor people ever. Maybe only show the crown in a duty if you specifically join via the roulette?