Mentors...please!

[Hatfright]

But being able to clear Expert Level Trials is a requirement (Heavy /s)

If I remember correctly, it's only for roulette, not the status itself.
Besides, mentor roulette doesn't require last expansion Ex Trials either. Other stuff can be cleared unsync just for the sake of it. SB Extremes can be a bother, but insignificant one if you're willing to give your group another shot after first wipe.
I doubt I'd be considered a "good player" in terms of content cleared or dps output, but even I almost finished with unlocking that roulette. To use it or not is another thing. I mean, if you do, you know what you sigh up for before you hit that "queue" button. Not "you" as "you in particular", but you get the idea.

I have never seen a party where mentors won't reply if people ask for help.

Lucky you.
In my 2 years of playing I've run into almost fully crowned parties with 1 or 2 newbies exeptions on Trials. My favorite was Moogle King run, where half of crowns tried to burn king down ignoring adds on second half of the fight (was jealous of the shinier crown, I suppose), and one idiot messed up target marks everytime it were correctly put to help new people get an idea of what needs to be done. Funniest part was blaming healers for not saving them from raidwipe aoe twice in a row. Makes you wonder how many of those crowned ones got the status just for the sake of it with no intent to be somewhat helpful. And that's just one example. Extreme, to be sure, but still.
Yes, there's trolls with crown and without it, but from people who supposed to help you'd think you can expect a little decency at least.