This is quite a rabbithole that will take some time to read...
Short version from what I gathered.
I. The admins and mods of this site oppose Online play variants of games being pirated. Such as 3DXchat. They were okay with it having the offline version, but with online server they only tolerated it enough since it goes against site rules.
II. The 3DXChat pirated online community had a bit of toxicity involving it that caused problems within the forum in discussion on the game topic. Basically users arguing and doing other disruptive s***posting.
III. There were theories of malware being in the online 3DXchat client that was being pirated. I don't know how true or not those claims were as there was a bit back and forth on that subject as well. So don't hold this to utmost of credibility compared to former two matters.