No one has said that there will be pointlessly low exp from mobs, just that questing will be faster. In fact it may only be faster solo. You never know until you start.

A good thing to consider is that there's currently an endgame exp grind (spiritbond), which would be after the last stop on the rails.

If mobs give no exp then how do they expect us to SB? Well... I think the answer is that mobs give exp.