Most people don't want to run their own mail servers. That isn't the same thing as saying we need a single entity to be in charge of email. There are thousands of independent email providers. Your emails get marked as spam if you have two users, not if you have two thousand. And small providers getting marked as spam isn't because it's necessary to prevent spam, it's because large providers would rather kill them on purpose and force more people to use them. Which we could fix it if we wanted to.
Everything could work this way, and should. You don't run your own social network instance, but you can, and thousands of independent entities do, and you can take your pick of them and move between them.
And we can learn lessons from the past. Major one from email: Addresses should be portable, or at least have zero-cost permanent forwarding built into the protocol.