What is up with d6 Star Wars?
I joined the site for a Star Wars game. I've tried several over the years I've been here. Only found one that's kept its legs underneath it (thanks, Ron!)
That said, I've had similar experiences with several freeform games, a couple of Shadowrun games (although I did manage to find one to play through to completion...or, at least, as far as the GM intended it to go. I felt like my character was left dangling with a lot of unfinished business, but...that's life), two or three Scion games, a couple of White Wolf/WoD games, multiple Serenity games...
So, no, this problem is not system-exclusive. It is, if you will, an occupational hazard of play-by-post gaming.