I get a sense that people (including me) hesitate to be the very first to post in a community after a few weeks or more without activity.

I think there’s no real need for that, even if that post doesn’t get traction, chances are there will be a post inspired by that post which starts a cycle.

I suggest people who are worried about visibility try posting in a small community, and then crosspost it to a popular community (e.g. posting an Age of Empires discussion in both !games@sh.itjust.works and !ageofempires@sopuli.xyz), until things get off the ground.