Lifers and transients (and all points in between): how is the forum used?

In the few months I've been on here, I've tried to discern how people use it. While I'm reassured by some people seeming to be long-term regulars, others who pop up and have really interesting things to ask or share, or put things in a really thought-provoking way, burn brightly for a while and then vanish overnight, seldom or never returning. I suppose a certain amount of transience is inevitable, so I'm not really sure what my point is. Maybe just that I'm confused as to why more don't stick around, continue to benefit from shared expereinces and so on. 

To those who have been around more consistently over a long while, or intend to be 'lifers' (as I tend to be when I latch onto a supportive online community), do you find it sometimes disconcerting or demoralising to put thought and care into connecting/sharing things with interesting and sympatico people, only to have them vanish in a sudden puff of apparent disinterest and never return. 

I suppose one hard lesson I have to keep re-learning in life is that other's moods and inclinations can be very mercurial. You have to take them as you find them I suppose for as long as they stick around. Fleeting interactions can still be meaningful ones I guess. The confusion and melancholy I feel about such things doesn't seem to predominate in many others - I suppose I find lack of continuity in others' patterns of behaviour more disconcerting than most NTs would. But I'm also a little surprised that that NT-like behaviour is just as prevalent in this neurodivergent forum as it is 'out there'. 

Or maybe I haven't been around long enough to fairly assess that. Not sure.