The issue that SCHs have with Dissipation is how it's supposed to fit into the kit vs how the player base actually uses it.

Point blank, Dissipation is for healing, not DPS, but because of how the skill is structured no one plans to use it for healing, only DPS and prior to Endwalker MP recovery. The issues come from how the skill acts and interacts with the rest of the kit. No other healer has to lose access to a good portion of their skills for using one skill.

The main issue is the healing buff which only effects spells, so no Aetherflow heals at all. And a majority of SCH heals are abilities not spells. The removal of the faerie isn't so bad as others have indicated you can spend the faerie skills prior to using Dissipation, but that's not something you should need to do. Why do we have to lose access to some of our kit at all. The biggest issue with the faerie's removal was having to resummon her afterwards, which thankfully was fixed in Shadowbringers.

Since it's inception Dissipation has had poor reviews. Players have figured out ways to use it, but its not a good skill. The skill needs an entire rework of some kind.