The problem with the FFXI version was it was never actually used how it was meant to, and was just something players set beside their names to inflate their own egos - few, if any, of the many players I met in FFXI who had the 'mentor' icon even knew the meaning of the word.
Although such a system might have some benefit to encouraging players to help new people in ARR, really, I don't see why we need something like that to do that anyway - as current players we should do it regardless - we see a new person needing help, we help them. It's as simple as that.
It's an ideal I've tried to uphold ever since I first started playing in FFXI, that because of all the help people gave me when I started, I made a commitment to myself that when I 'came of age' in the game I would do everything I could to return the favour and help out any new person I found who needed it. And I've carried that ideal into FFXIV as well.
As the line in
Answers says,
"Look to those who walked before, to lead those who walk after." 