Was thinking along these lines earlier when I saw that Mastodon now has something north of 7M users (including bots? are there many bots there? some, for sure,

Was thinking along these lines earlier when I saw that Mastodon now has something north of 7M users (including bots? are there many bots there? some, for sure, but probably not a lot). 7M is the population of a good-size city. Twitter has something like 24M/day active (including bots. lots of bots!). The difference is that Twitter is just one big, wide-open agora, lots of touts shouting at the tops of their voices, and heard over all the space. Mastodon instances are natural neighbourhoods. You eventually find one that suits you and settle there. You don't like it after a while, or you find somewhere better, you move. You can very easily avoid the dodgy parts of the city (or visit them if that's your thing) and just hang out where you're comfortable. For me that's the key difference between the two.