Mentors...please!

[Jojoya]

True, but that's again not the point here. The point is, you don't need tp be a mentor to expain the basics of the job (which was what I was arguing in the first place). If someone didn't understand the basics after leveling from 70 to 80 (which requires approximately 20 hours of play time, more than many full games), he's not the kind of player that would pay attention to what a mentor says. What's the chance of knowing absolutely nothing about you job after 20 hours of gameplay? Close to zero. Even if you used a jump potion. That's why mentors should be something more than casual players that know general info about the game and the basics of the three roles.
The thing is, there's nothing in this game that certifies your skill except for (current) savage and ultimate achievements, but that's probably a bit too much to ask of mentors.

You keep assuming that the point of a mentor is to be an expert capable of teaching others how to play every job.

This is SE's entire description for mentors:

The mentor system provides more experienced players a means to offer advice and guidance to newer players.

- What is a mentor?
Mentors are veteran players who chose to offer their time and experience to help guide new adventurers. To facilitate their assistance, mentors will gain access to a special chat channel as well as a means to easily register for duties and trials with new players.

It doesn't state you need to be expert in anything. You just need to be open to helping new players.

Most new players don't care about the specifics on how to maximize their job efficiency. A lot of them don't care about playing their jobs well at all.

What are the questions I most commonly see getting asked by new players in Novice Network? "How I do sell things to other players?" "When do I get a mount?" "Why can't I get the glamour dresser to work?" "How do I get a chocobo that isn't yellow?" "I want to try a different class, what do I need to do?" "Where do I go to unlock this?" "How do I get promoted in my GC?"

Occasionally you get the "which job is better to play" question asked but it's not that often. It's extremely rare I see a new player asking "Can someone tell me how to play my job better?" Those that do ask are immediately directed to The Balance discord since it's something better answered there than in game.

You don't need to be an expert at playing a job to answer the basic questions new players usually ask. You just need to be willing to help.

[Deceptus]

It doesn't state you need to be expert in anything. You just need to be open to helping new players.

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