Not only is Nostr relays are orders of magnitudes fewer, and less time tested. and dns dependent. They are also not cheap to run AND have a conflict of interest since they double as service providers

This is the Mastodon and even Email fault, where the service providers can boycott and censor other providers.

But Mainline is cheap, extremely redundant and have no interest whatsoever in what is published on it. They don't compete with the services that are published on it.

This is significant in my opinion, you can't dismiss all of this merely as difference of degree... at some point it becomes difference in kind.