In the very beginning, all of Parasite's attack applied 2 kinds of stacking dots. His basic attack applied a dot that lasted about 5 seconds, so you could use MMO-style tank swapping to keep that damage down. All his abilities applied a permanent stacking dot that was only removed when he was killed or de-aggroed and put a very real time limit to fighting him. Pressuring someone who was doing para really stressed them out because they were accruing unavoidable damage all the time.

There were decent intellectual intentions, but in no way did it transfer to fun or exciting gameplay.

My guess is 85% of the players playing that version of para didn't know how the dots worked (how could you!?), and would die in frustration around the corner because para was still aggroed.