The key thing folks keep messing up is that you can't centralize identity and get what you want, but centralizing identity is what makes the most money. Having the most money means your software is "nicer" (or simply more addictive, or better marketed) and creates its own gravity well.
Many have looked for technical mechanism by which to solve this (see also: Mastodon), but I believe the only real solution is a better governance model that resists monetizing relationships and prioritizes the strength of community bonds over dollars. With all of that, we might have a chance. Otherwise we will always be fighting the tides.
Put another way: Yes, it's important to figure out how sites could be connected or federated, but more important to figure out how you keep eyes on that ball over the course of decades.
