Quest based leveling: Future problem?

[Felis]

Actually, Yoshi said that mob-grinding would not be viable, and that there would be quest-based progression (which would be the ideal way to level). And this thread is just a concern that quest-based progression doesn't make sense unless there's repeatable or self-directed content.

He said "contend-based progression"

And don't overlook this:

Y: There are lots of contents to choose from so we have it set where the obtainable EXP isn’t good just by doing one. For those who want to gain EXP efficiently I think it’s best to do different stuff equally.

So, doing only quests is not the best way.