> That app is doomed to obscurity.

Quite arrogant to assume that an app not supporting /your/ specific note-taking workflow means it's "doomed to obscurity". It's a popular app with plenty of users, a healthy plugin community, and a team of six building it. I think that pretty obviously proves you wrong.

If you were actually interested in trying it out, you could've simply run a quick find command.

find . -name "*.txt" -exec rename -v 's/\.txt$/\.md/i' {} \;

So simple you can fix the problem in one line but me pointing that out as bad design is arrogance. Gotcha.

There's a plugin that adds support for txt files: https://github.com/deathau/txt-as-md-obsidian

Converting all files from .txt extension to .md extension would be enough to start. This I what I did.

The only annoying thing was that in my text files I often used indentation to group stuff and in markdown indented text is treated as code block.