Would the fediverse see new adoption if some of the decentralized aspects were abstracted away? I'm thinking of a “meta” instance, where an admin might cobble together Pixelfed, Mastodon, and WriteFreely to build a single Myspace / SpaceHey site. The profile could be as simple as a Linktree-esque page with a profile image and links to each content type: Photos, Notes, Articles (for each respective underlying platform). Then each platform might share the same design / theme. Or it could be as complex as a unified profile where content from each platform is displayed inline. That should be possible if this “meta” instance was a client to all of those platforms.
Of course, you already have some platforms that combine all of these media types into a single place, Facebook-like. The benefit of this “meta” instance over that is that the pieces are now composable. You could swap in Pleroma for Mastodon, or Plume for WriteFreely, or leave any pieces out, depending on what you're going for. With this, each “meta” instance is more unique, and can develop into its own full-fledged community; a sort of digital town connected to other digital towns in the wider fediverse.