Originally Posted by
Semirhage
That's not -entirely- true. Bosses have a hard limit of 60 debuffs, but you can only see 30 at a time. If your debuffs get applied after those first 30, it gets hidden in the invisible box of 30 debuffs that don't show up on screen. They may have fixed this, but it was definitely true in late Heavensward, shortly after which they started trimming DoTs. It was very annoying to cast your DoTs on an enemy and not know whether it was there or not, but you could tell it was there if you had any procs based on them (like BLM).