Sure, 'ability to scale' (scalability) might be an issue, but if you are using it, you will see that the majority pf people are on other servers or communities,

Sure, 'ability to scale' (scalability) might be an issue, but if you are using it, you will see that the majority pf people are on other servers or communities, some not even using Mastodon. Mastodon itself is just one of the implementations of the federated protocol that uses ActivityPub. A lot of alternatives exists, like misskey, pleroma, etc.