Why I lost all of my blog's comments
Basically, I was a fool.
I had my Juvia setup running on a single server in AWS, with a standalone mySQL server.
My setup auto-updated every time a new version of Juvia was released, which never happened until a couple of days ago, as the project is relatively unmaintained.
I also neglected to backup my DB, as I'm stupid.
A couple of days ago, the Juvia project got a new code of conduct. As part of this, they released a new version, which caused my setup to auto-update, wiping my DB.
Why move to Disqus
I decided to move to a managed comment service.
In retrospect, maintaining my Juvia setup was way more effort than it's worth, as I never really customized it, and I neglected to take basic actions (e.g. DB backup, SSL setup).
I saw that Disqus offers guest commenting (although it's relatively hidden), and allows you to export comments to a file. This means that if I'm unhappy with the platform, I can migrate away.
Sounds like a good deal.