To me, the issue isn't the displaying of all the debuffs and dots, but actually the raid bosses being full and no more can be added until something wears off or is overwritten by the same player. :| I do remember also that SE mentioned in the old patches that the limit is 60. In 24-man content only 3 dots from every class would mean not everyone could fit theirs in. During hunts I lost count how many times "aero does xx dmg (no effect)" messages I got.

I just don't know how it counts towards the number when the boss have something like immunity to virus.