Call me crazy, but I've never seen this happen in duty finder...like ever. Is it just more common in the mentor roulette or something? Maybe I've just been lucky. :V

Even in stuff below 70 it's maybe happened a rare couple of times (In HW and older content really) and it was always a healer not using any attacks and only healing. Above 70? Never.

I agree with you of course, I'm just thinking it's not that common of an occurrence.