It seems to me the best shot for a new user to spark engagement is not to just cold post a note to the world - but rather, to start participating in already engaging conversations. So, maybe the default feed for new users ought to be recent trending notes (like within the last hour at most)... and hopefully, they can come up with something of value to add.

Of course, this still doesn't guarantee anyone will follow you - but that kinda seems more like a reality of life than a challenge for nostr. 🤷