Warning: Wall of Text Analysis for the King's Fall Raid below:
Played through the Raid with some on DGAF on Friday night. Made good time until we got to the Daughters. I've come to the conclusion that it is by far the worst raid encounter in the game. I hope this doesn't come across as salt. I've failed hard and long at bosses before. But failing at the Sisters felt different. Felt bad. And I tried to think why.
Each raid has a final room with two boss fights in it, and King's Fall is no exception. Vault of Glass has Gatekeepers barring the way to Atheon. Ir Yut guards Crota's Crystal before he's summoned. And the Daughters something something before Oryx. (Maybe the lore can explain, but it's not rendered in the encounter. The first failure.) The function of the first fight is to teach any new boss mechanics before the final boss appears and/or to familiarize people with the arena. Ir Yut really only familiarizes players with the arena, but it works thematically at least. Gatekeepers teach the portal & relic mechanics and crucially they have their own mechanics just to them. Kill the Gatekeepers. Defend the Conflux. Those are on top of the shared Atheon mechanics of managing debuffs, guarding plates, etc.
The Daughters, however, have 0 mechanics to themselves. They tear people, then wait impotently until someone grabs a relic. Then they flail about on their platforms as we shoot them to death. This is the exact mechanic that we use on Oryx. There are no additional mechanics or targets. They are boring, bland bosses and you could cut them from the raid and no one would care. (And let's not discuss how trivial the damage phase is when everyone is running Touch of Malice.) Worse, there's really very little variation that's allowed. Five players have positions defined for them. And one guy can float. Gatekeepers can be tackled any number of ways. One side then the other or both at the same time, etc. The Daughters only variance is where the runner should stand, but there's an optimal choice now, so yeah.
So why are they there then? The Daughters were obviously implemented to combat the Atheon "bug" of players being able to make their own fate and decide who got to run the relic. The Daughters randomly tearing a fireteam member forces all players to learn how to run the platforms. An admirable goal, but it does such a terrible job at this that I'm staggered. Our team was made up of people who had only successfully completed the Daughters once or were complete newbies. We wiped on the Daughters for 1.5 hours. And that's not because what you're asked to do is hard. It's because it doesn't allow for learning. If you get torn and fail, you may or may not get another chance for 40 minutes. You can't count on being able to try again when your mistake is fresh to learn from it. This is why so many of our runs failed. You do learn it after a while, but if you gave people the chance to consistently run, even if you made everyone do it, it'd be so much faster. The difficulty for the Daughters comes from them randomly picking unprepared people and then not picking them again in sufficient time for them to learn.
Additionally, the mechanic is unfamiliar and small mistakes are not recoverable. Fail to kill adds well with the Brand in the War Priest, well, your damage phase is short. Fail to get the Gaze on Golgoroth, your damage phase is short. In both cases, the mechanic is a) familiar to people (shoot stuff) and b) can be recovered either independently or by the team on the next damage phase. The Daughters ask people to a) do the unfamiliar (jumping in 3rd person, in a combat phase, and with so much stuff on your screen you can barely see) and b) any tiny failure is unrecoverable and results in a wipe.
To be clear: The Daughters are not hard. At all. Learning the platforming is hard. That's it. Once everyone does know it, then the encounter is trivial. It's an easy minute-and-half. So it fails in that regard as well. (The Gatekeepers is still a fun, dynamic challenge, even when we did it as 34s.)
From a standpoint of justifying their own existence in the raid, the Daughters fight doesn't provide any in-game lore reason for them being there. It fails to provide even one unique mechanic to make them a satisfying boss. Finally, its challenge (and thus interest for raiders who are expected to run this weekly, if not more than that) only exists for new players.