^
This, just properly level your Aetherpool gear.
If your gear isn't at least +50 by the time you reach floor 81+, reset your progress and start going back up from floor 51 lest you become the one keeping back your party.
Can confirm it's possible with no healer. Did it as a pld tank with 3 deeps up to floor 90 , though I had to spend a bit of time spamming Clemency on myself... and the deeps and other tank when they got hit by Pox. Other tank was a drk, so I was pretty much a budget whm, but it's possible.
Cleared it yesterday with level 33 gear, granted my friend was the healer. rest of the group was mostly dps except for some floors we had tanks
Cleared 91-100 with 4 dps.
The biggest issue is that people get into 51 and above and keep trying to run as if it was lvl 1-50. That just won't work. I finished multiple times with no Tank but I have to admit that with no healer it is a bit frustrating because the ubber (in their mind only) NIN's and DRG's seem to think that they are immune to death. I once wiped 6 times in a row before we cleared 3 times in a row. So team work is what gets you through 51-100 the gear does help as long as it is over 30 and it scales up pretty quick once you are able to finish floors, and clear bosses.
I keep getting people that are running 51-100 as a class with no job crystal. I have seen Rogues, Thaumaturge, Arcanist, etc. I called out an Arcanist (I wasn't rude, I just said "really, no job crystal?") and was basically told by the group to shut up because it's casual content and they can do what they want. Excuse me for not wanting to potentially waste an hour picking up slack for someone who is missing half of their abilities.....it's just rude.