That's a good question.
I'd say it's because chans are just so damn slow, nobody likes waiting around for some rando to come and answer a thread that got posted three days earlier.
> >Be me
> >Be on some random social media
> >Post a thing, wait five minutes.
> >Six hundred answers!
> >Be me.
> >Be on some random chan.
> >Post something
> >Come back three weeks later.
> >Still no responses