Many of us have documents from the early 2000s that no longer open properly. The programs that created them are gone, and the converters that remain get the formatting subtly wrong.
Text files from the same period open instantly, on any machine, in any editor. They search well, compress well, diff well, and survive every migration between operating systems and backup tools.
A little structure goes a long way
Plain text does not have to mean unstructured. Markdown adds headings, lists and links without hiding anything behind a binary format. CSV covers tables. Both are readable by humans first and programs second, which is exactly the right order.
Write for the reader who opens the file in thirty years with whatever editor they happen to have.
Writes about tools, habits and the quiet craft of keeping things running.
