Level 50 Zones need to reward experience...

[KisaiTenshi]

The dungeons themselve don't reward experience?

Only if you never cleared it with that job before.

And the logical reason for this is so players aren't spamming them to powerlevel. It's still level 50 content, which you need for the storyline bits to get to HW.

But it's mostly a jokey faceroll now that item sync is to HQ.