Oh, I know there are quite a few groups doing the newcomer welcome thing... of course most are (understandably) bot messages, which people are mostly trained to ignore.
I'm more thinking along the lines of guidelines/FAQ being popped in people's faces before they even get to posting. As part of the account creation process, even. Along with "have you REALLY backed u your keys?" you get a "if you want ANY chance of succeeding, read this!" Maybe even having "annoying popups" before someone tries to post.
I've tried to talk a number of people into joining Hive (as has my wife) and the issues always seem fairly consistent: The learning curve is "too long," and people arrive with false expectations.
The other "problem" we have is that there's only a very tenuous connection between someone who "recommends" Hive and the person actually taking them up on the offer.
The referral system might let me know that someone joined as a result of my linking from somewhere, but I have no means of DIRECTLY sending them a "Hi Erika, how cool that you joined Hive! Here let me offer you some help and suggestions! from the very beginning. I've been saying for 5+ years that we need an integrated internal message system — Facebook messenger style — in this ecosystem. I can cost resource credits, but doesn't reward, and to facilitate newcomer integration, there should be an option for the original conversation starter to "fund all resource credits for thread/conversation."
Or something like that.
Mind you, as a long time admin/sysop in web groups for 20+ years, even 5% of signups becoming active would be a MAJOR success!