Anyway, not following bad changes by meta would leave people where?
Exactly where they are right now.
In that case, Meta joining the fediverse would have been a failed experiment.
Not really, in the greater context of meta controlling the vast majority of fediverse we would be the ones that are a failed experiment, a niche group of old people yelling at clouds, not willing to get with the times and join the instance that has all the content, all the users and all the new tech improvements. Just look at how much shit beehaw got for temporarily defederating the 2 largest lemmy instances, now imagine when that happens to your instance and it gets cut off from meta permanently. It'd be like trying to maintain a twitter competitor while twitter was still in its golden age.
Billions of people using interoparable software to talk to each other. Email is a brilliant success!
People don't create private instances or join smaller communities for their email provider, they go to gmail, hotmai or even protonmail for the promise of stability, safety and compatibility with others, not getting listed as spam bots or their mail going straight into trash. Companies have dedicated people to handle this but in my experience even they just end up using microsoft or google software in the background, just with their custom domain. It is a big success for email and these corporations, it is a terrible story for the open and community-controlled internet and fediverse.