When judging bitcointalk, you should keep in mind that forums are not as popular as they used to be, that's the simple fact and in that regard bitcointalk ain't no different than many others. I've been active on various forums (and still am) for ~20 years, and situation is pretty much similar everywhere; old users are becoming less active (which is perfectly natural) while younger generations have bunch of options nowadays that those in the late 90s/early 00s didn't have.