I’ll have to give it a try
I think it mainly comes down to the project landing page being more friendly and the UI being more polished.
The landing page of join-lemmy.org doesn’t show what the website looks like. The only screenshots are of code and github. That section is geared towards potential instance administrators, not potential users.
I just set one up via DigitalOcean and it was easy peasy. I’ll see how it goes and move it if needed.
Interesting article, I don’t think I have a use for them though.