It's also incredibly easy to misplace files and forget that you wrote notes altogether. I've lost many notes.txt throughout the years. I've recently forced myself to use Evernote, which for me is better than any file-based system, but it is a bottomless pit with poor discoverability. A physical object doubles as a reminder.

With respect, that seems like less of a problem of digital note-taking in general, and more of a problem of the specific digital note-taking systems you have tried. Using notes.txt files is a bit like writing notes on napkins and leaving them scattered about. I don't know anything about Evernote, but I'd be interested to hear what issues you had.

What works for me is taking notes via email. Backing up, organizing, searching, and distributing email is more-or-less a solved problem, and my note-taking inherits those solutions. I can read and add notes from my phone and from my computer, with the ability to choose from a plethora of applications. I have multiple backups of my email around the world via standard email syncing. My email host has been 100% reliable in not losing my emails, as well. If I want to migrate to a different email host, that is trivial.

That's a solution I might want to try. But how do you differentiate between your notes and the dozens of emails you receive every day? You can filter by sender, but then you often get your sent mail, depending of how filtering is set up in the email client.

I have my notes at work as org files, and simply added them to a git repository.

And in my case, it can be read. Important, as my hand writing is atrocious!