Or YOU
-John
Heck, for all you all know, it could be me. It could even be GX1_Man... or perhaps Merlin_2 was even a residence of Mac.
Split personalities, or schizophrenias, is a rare disorder, but it completely possible.
If Mac did have such a disorder, md's, or even himself, for his own well being, may have considered the internet a "safe zone", like a cushy room. He cant hurt himself or someone else (excluding mental), but he can cause a LOT of confusion.
Nevertheless, Mac was a problem, and most likely, that problem was solved.