@CassandraVert That is exactly the right question to be asking. At the moment open means access to a lot more people and content. And there are a lot of services like kbin, Lemmy, pixelfed beyond mastodon that work reasonably well together.
But that's just the start. Open versions of closed systems (Twitter, Reddit, Instagram, etc) are very useful to have but it'll be exciting to see what innovative new directions these services can go and what totally new services launch next year.