E-mail spam filter is funded by google and other multibillion megacorporations though, and they just outright block or rate limit unknown providers. I'd say it's not gonna be as easy to do it with fediverse.
This is why yes, there needs to be a feed algorithm. “Just show it to me chronologically” is the most naive thought
Agreed 100% but again, I wonder if we have enough resources to actually make it good while also keeping it free, both in terms of monetization and in terms of outside influence and biases. Twitter and others spend a lot of manhours on it and mastodon still doesn't have it either for example, it's not even being worked on afaik (or nobody talks about it).