You know that high lvl dungeons have part of their monsters immune to CC right.
Also most CCS uses some form of knockback and usually do more harm than good (unless someone is in a pinch) as you will probably split the stacked monsters, leaving some of them to be dealt with individually as they were kbed out of the AE purge.
And sleep is a lackluster CC in dungeons, it lasts maybe a second when your group is unleashing dozens of hits in the monsters.
Fact is, you will be hit, you will have downtime and most of the time that downtime will lead to the dungeon timer expiring before you kill the last boss if you are planning a full clear.
the meta right now is:
-healer: full clear
-no healer: boss rush
the exception being when you have a AoE demolish squad party that just vaporizes the mosnters before they can do much harm.
The average party search group cant complete a dungeon in time without a healer, doesnt matter if you can play bash pingpong with the few monsters that are affected by it.
As i said, raising bonfire regen in dungeons is a much easier fix and much less intrusive as requiring a healer.