I'm not 100% sure, but I can almost guarantee that most of the 383 online were bots.
Regardless, yeah, it's happening, and for a number of reasons.
First off, our cars are old. The newest car we discuss (or at least that this forum specifically caters to) is almost 14 years old. Some of them are pushing 20 years old.
That said, some of the original members of this board most likely have sent their cars off to the junkyard above. Don't forget, not everyone wants to hassle with an old slow car when they would rather have, and can afford, a newer car.
So most of the old-timers have moved on. morgie, mile hi, 91White-T, boostjunkie, IggDawg, AdamBC5, even the administrator himself (much love Dave

), have all moved on from 1st-gen Legacies. In fact, the only people I can think of off the top of my head that are charter members of this forum and still have their Legacies are Josh (777), Andrew (petridish38) and me. I'm not a true honest charter member, but pretty close. And Andrew hardly ever posts anymore (he still has his Legacy, but it's a secondary car to his WRX, so he doesn't drive it much).
Second, we've all been toying with these cars for quite a while. So we either already know how to fix stuff, or if we're building a fast car, we've already pushed it to its limits pretty much. Truth be told, there isn't a whole lot to talk about that hasn't already been said before.
Third, I think the atmosphere that once surrounded this forum has worn off a lot. I won't go into that.
It happens.