Some of those are relatively decent explainers, but what's needed is simplification of the whole onboarding process and UX. Having to read a 2000-word treatise on the Fediverse doesn't solve the problem of the Fediverse being confusing in the first place. :)
To me, the solution is a streamlined onboarding, like I've proposed, driving most people toward one or two common, popular instances where they can just sign up and just find posts that interest them — then let them/help them discover how to further explore once they've got the hang of it.
You can't read about how to use Lemmy any more than you can read about how to ride a bike. And yet, most of the pople trying to drive Lemmy adoption are explaining, explaining, explaining instead of trying to make it simple.
I'm not saying those explainers shouldn't exist. I'm saying they only help people who want to understand Lemmy rather than helping people who just want somewhere to go for a feed of interesting community topics.
Actually, that Reddit post was exactly the thing that got me thinking about this in the first place. That is not a post for average people. It starts out with an attempt at a simple explanation — "No need to understand federation, servers, or any technical jargon" — but very quickly devolves into exactly those things it said you didn't need to understand. For example, it uses the word "server" 21 times without ever explaining what the word means. And, as I mentioned elsewhere, explainers shouldn't be necessary. What's needed is a cleaner, simpler UX. I've started by suggesting a clearer, simpler onboarding process. The rest I'm still noodling.