Yes, by comparison, approximately no one in the world has heard of PeerTube, Friendica, Mastodon or Disapora. And even of those that have heard of them, few actually use them. Centralized platforms for these things are simply so much more convenient and discoverable that there really is no competition.
Look at the speed with which WhatsApp was adopted (talking about before the FB acquisition), and compare to Mastodon or Diaspora - there is no contest.
Mastodon is big news in India at the moment, to the point that some newspapers are trying to pretend it's centralised and "hates right-wing people" (because one instance refused an account to a police organisation).
If it's getting newspaper coverage, it's probably not all that niche.
None of those are your own platform. You have a share in them. Their value isn't in being "your own", it's explicitly in being "nobody's own" or "everyone's", depending on how you read it.
If you somehow use them only for yourself so they run effectively as "your own" (assuming you can and want to isolate them) you run into the same issues I mentioned above.
Your comment in brackets applies very much now ;).
(It's fine to assert things, but make sure you're right first. Asserting things you don't know to be true is disingenuous, and a bad habit.)