"I’ve seen many similar pleas recently whenever any popular, free web service has problems: “Please, let us pay you so there won’t be any problems!”
But it’s an impossible dream. If a web service is popular enough that you hear about it when it has downtime or major issues, it’s probably a large, very complex system. 100% uptime is effectively impossible."
As for being able to own your data and store local backups, you can do that with Gmail POP, or with Gmail IMAP and an email client that'll store messages locally.
(The author's argument that Gmail IMAP is buggy, is one anecdote; I can provide my own anecdote to the contrary. Again, we'd need some data to prove that FastMail is better.)
This is true, but his solution is not one that must use FastMail. His address is his own, and he backs up his own email. So if FastMail lost everything of his, he would be able to switch over to something else. That he owns his own email address is the important factor, not that he happens to use FastMail.
For the record, I use Gmail for all of my personal email, and I don't bother keeping backups.