But then you could run some open source server that does it, just not typically from your home. It’s the home part that won’t work, just as most people don’t serve their web apps from home. And non tech people can still outsource and move between competing providers rather than have an oligopoly of social media companies.

Sadly publishing goes towards the lowest friction service. Was websites, then blogs, now Twitter. The backgrounds and themes weren’t as important as simple content. I’m not sure home hosting has any chance to beat that trend.