the fediverse's complexity wouldn't matter as much if enough that people cared about was around

I don't need to have the majority of people in my social media. The ones that care are that ones that matter.

People are dumb, especially with anything new. Any intelligence filter excludes a substantial portion of the population. There are a large range of personalities and functional thought in humans. There is no universal low-bar barrier to entry. This is why it is so effective to exploit old familiar paths of branding or taking over an existing user base like with many American brands or like Twit-X