I don’t fully understand how lemmy works completely yet. But for example I made an account at Division by zero and subscribe here to post. Is it not just a more inconvenient version of making a reddit account and being able to post practically anywhere?
Also what’s the difference between making an account at one instant and just making one centralized account for the social media?
Every social media has tended towards awfulness (Facebook and Twitter being two most glaring examples) to the point where it impacts the user experience, because the companies have to make money somehow. If you’re using the service for free, that means figuring out how they can use you as a resource for other people to be able to do something profitable with you, and engineering the site to encourage you to do things that will make somebody money, instead of what you’d like to do with the site. That’s why they eventually get infested with ads and user-hostile features to the point that they become unpleasant.
(Reddit is a little more complex; it’s still actively good as a source of links and memes and etc, but definitely degraded compared to what it used to be, i.e. well run AMAs, good conversation with a wide variety of people going in depth into their stories, creative outlets, well-informed people talking about tech and politics etc.)
A volunteer-run server won’t have that issue. It’ll have other significant issues (reliability and ease of use being the two obvious ones), but a lot of people in the modern world and almost everyone you’ll talk to here will feel that the tradeoff is worth it.