But there was another kind of damage done here, to the man's identity, location and voice. His blog and his email address were his public persona. He used his blog and his address as identity, and as his channel of communication with followers, other artists, and I assume most of his general online communication.
That persona no longer exists. He's been all but disappeared, and it's going to take a long time for him to reconnect.
The technical lesson that should be learned here, beyond backups, is to have your own domain. You can still use services with your own domain. I've used many ISPs and email services, and I've had the same domain since about 2000. I used to use gmail (with me@mydomain.com). I use fastmail now. I've never since 2000 had to tell anyone to change my email address, because it's never changed, even though providers changed. The subject of this article would have a much easier time of reconnecting, had he used his own domain.
(Added to that, in the "backup" theme, download all your email as it happens. I use thunderbird, and it does that for me. I once resolved a dispute with a former employer because I had email that they had no incentive to find.)
Using your own domain is not absolute protection, because you don't really own your domain, you rent it. Your registrar can decide to sell your domain to someone else, and if your consumer rights were violated it's going to be difficult to reclaim your domain. In the future I think we're going to need meta-domains that can't be transferred, that are our identity, but I don't know how that would be implemented.
I said this person has been disappeared, which was a provocative use of the word (this isn't Argentina or Chile in the seventies). But thinking more broadly, consider that as our lives are lived more and more online, any government could compel a provider to remove you. Even if it was unjust removal, it could be so expensive to restore your presence that you just can't do it. Harder to fight a government than it is to fight Google, if the government decides it won't be moved. We have a no-fly list now that has no associated due process. I can imagine a no-communicate list.
Which is all to say, try to be as self-sufficient as is practical, and as is warranted by the importance of your communication.