Mastodon/Lemmy instances can be forced to KYC you. So you would have to jump into hoops and move from instance to instance. It will be like torrent sites or darknet markets, that come and go.

Yes, you can self-host, and should, but most people don't want to be a sysadmin, and it isn't easy. Ideally you should be able to participate in a self-sovereign way without being a sysadmin. Just like:

• you can torrent something without being a sysadmin
• you can self-custody your cryptocurrency without being a sysadmin
• you can chat on SimpleX or Session and never be deplatformed without being a sysadmin
• you can use Nostr and never be deplatformed without being a sysadmin