All it means is that you won't steamroll things, and that you still will get karma/gold/exp that will help you out - not that you'll be getting the same rewards as on-level content.
So its more like:
A: I need a tank for ROTF.... anyone there?
B: I'm level 50 but I have some time, sure.
<B does ROTF and gets some Lv 50 experience instead of 0 exp (due to greyed mobs) and also gets a few plaques which he can also exchange for gear or experience items etc>
A: I'm Level 50 and don't want to do experts. Let's do normal ROTF!
B: I'm Level 50 as well! Screw experts! Screw raid content! ROTF gives GMOA and we can just grind ROTF over and over!
C: Can I join too? Doing these dungeons as a mentor is 100x easier and faster than the raids and expert dungeons anyway.
Trion still wants a gear and level based system. They just want to loosen the reins. So they give mentoring.
Just as Trion still wants a typical questing system along with specific dynamic events. They just want to loosen the reins. So they give Instant Adventure for 'on the fly' questing as a dynamic event of our own.
This is not GW2. This is not WoW. This is Rift, which tends to mix stuff up from previous games, together into a working model (hopefully).