Currently in the game there are two kinds of buffs and debuffs: Those with a name like Minor/Major Berserk and those without (like Elemental Catalyst). The ones without a name do stack with named buffs/debuffs. And thats the problem: Raid composition is build around bringing as much buffs/debuffs as possible. With the named buffs/debuffs you often have choices as to where to get them from but for the unnamed ones you have to bring the set or you don't have damage. It is also very hard to keep track of the amount of unnamed buffs/debuffs.
One example:
Olorime and Spell Power cure grant Major Courage which gives 430 spell/wpn damage. Powerful Assault gives ~407 spell/wpn damage without a name on it. So in a perfect group, you'd have to bring both. My suggestion would be to make Powerful Assault also grant Major Courage.
Another one:
Dragonknight Engulfing Flames gives up to 10% more flame damage taken as a debuff. In the new update there is Encratis’s Behemoth which increases flame damage taken by 5%. Both do stack. My suggestion would be to turn both debuffs into a new named debuff (e.g. Fire Vulnerability) which both grant 5% (for DK it would be regardless of spell damage). So you could bring either a DK or the Monster Set in the raid.
The new sets Kinras’s Wrath and Drake’s Rush already have named buffs, they are good examples how sets should be.
This should be applied to all the sets which gives unnamed debuffs like Alkosh, Powerful Assault, Elemental Catalyst, Z'ens Reddress, etc... If there is not a similar named buff/debuff then create a new one. And spread the debuffs and buffs more on sets and skills.