Starting in 2005, I've been keeping dated text files in a Log folder, organized by year and month. Anytime I need digital "scrap paper" I make sure I keep it. If I need to save files, I open instead a dated log folder.
There's a critical optimization problem here the young often get wrong. One needs to "Huffman code" the work put into organizing on entry, versus the work later in retrieving. For example, I save physical receipts into four rotating bins by quarter, then I vacuum pack the old receipts and stash them in the garage. Occasionally I save hundreds of dollars by proving I shipped something (and that would be a receipt I probably scanned) but any more work than this on entry would be a mistake.
It's the complete lack of organizational structure, other than date, that make my log files so useful. I instead get good at including keywords, always asking how I would find this later. I never have to wonder whether I filed this under "garden" or "tomatoes", resorting to a system-wide search. And this system has survived many editor migrations.
I agree with the arguments not to use a commercial system. That's like putting an aspirational cookbook on your coffee table. Org Mode is also too structured on entry to be optimal for me.