The reason I say Tim W is important is that in a lot of other horror media, especially the ones dealing with “eldritch” creatures, “going crazy” is treated as an endgame state, equivalent to being dead. Once you go crazy, you’re out of the story. Game Over.
But in Marble Hornets, we have Tim W, a character who has very definitely been “driven crazy” by his experiences, but is very much still an active player in the story. He’s mentally ill as a result of The Operator’s influence but he still gets to be a human being.
I have more kind of half-formed thoughts about how mental illness is used as a threat (both in horror in general and in MH specifically) but I need to mull over that some more. Suffice it to say that in Marble Hornets, mental illness is not the worst thing that can happen to a person and that’s a nice change of pace.