Not everyone has access to a $100 server, reliable power, and unmetered internet, let alone the knowledge and time to be their own sysadmin.
What if organizations in a position to do so, from mobile phone operators to ISPs to public libraries, provided some basic level of content hosting with standardized content management APIs? People with the means and motivation could host their own, but most people wouldn't have to. Perhaps that could pave the way for universal front-end tools and independence from the social media giants?
Related: It looks like someone is trying to address the issue by layering a social media experience atop an existing distributed messaging system (Matrix): https://www.kombuchaprivacy.com/circles/