@moon.eth
Farcaster is left out, as was Nostr, because many users on other networks are openly contemptuous of crypto-related things and won't "promote" them by acknowledging their existence no matter how popular.
Incidentally, "Mastodon" software only has a 500-character limit but the Fediverse, which is the actual social network that Mastodon brand co-opted, has no built-in limit and many compatible servers are quite higher. My server has 20,000 characters. Mastodon itself will happily display posts higher than 500, it just won't let you post your own.