Maybe because attention on Twitter (thus on Mastodon and Pleroma) is deliberately scarce, which makes valuable contents hard to find. A pretty bad microblogging service if you ask me.
I don't know why but I feel like scarcity is interpreted as environmental pressure and for this reason creates extrinsic motivation, as the need to have better relationships with your environment – until the urban and normalized, but pathological point where you're trapped in it.