@swetland @mcc @cthos @aeva Mostly true, but Pleroma and Misskey have most of the same features, and are simpler to install, yet haven't supplanted Mastodon.
I think the true killer feature of a "better Mastodon" would have to be in-place migration: allow upgrading an existing Mastodon server by reading its entire database, and provide a UI similar enough to Mastodon that it's a seamless transition for users.