Thanks for this ! User retention is something I've been thinking hard about. While I appreciate it shouldn't be all about the money, I think that author and curator rewards is something that is new and exciting for those who (like me) come from legacy social media where you get nothing from a post except more adverts. So leveraging that is definitely worthwhile.

I didn't realise that the onboarding post thing was such a huge indicator. Perhaps what is needed (and I appreciate I'm suggesting something which creates a lot of work for other people !) is to try to persuade the main front-ends to have a kind of onboarding tutorial. Hivebuzz does something like this already, but of course you have to know it's there.

I'm thinking that for new users, there could be the kind of guided tutorial similar to the way video games do it. So once you click "yes" to the guided tutorial, it takes you straight to an onboarding post screen pre-populated with tags and with bubbles explaining what each thing is and with some suggestions on what to put. Once the onboarding post is done, it could move on to "here are some suggested communities. Join a few you like" and then "read some posts, and here is how to upvote them". Effectively, it would teach new users all the key functionality as well as pitfalls to avoid.

Perhaps the front ends could even auto-join new users to a "New User Community" for a period of (say) 6 weeks, or highlight their names in green or something to make it easier for us all to spot them.

User retention is hard when there are so many things competing for our time !