Part of their problem is that they aren’t.

But they should be just text files with pointers to non-text things.

Creating a proprietary format just because is an unnecessary complexity and cost.

I used Evernote for 5-10 years and had thousands of notes. I had maybe 10-20 photographs or diagrams mixed in, but mostly it was text.

Not sure how common my use is, but they kept adding stuff I didn’t want. And it’s now a “free” feature in Apple notes, onenote and countless others.

I think the difference is that Microsoft and Apple are just trying to find efficient ways to store data in their cloud storage. Evernote was trying to find ways to make customers pay for note taking.

No. But I’ve pretty much always come back to storing text files, photos, and PDFs. It may not be as elegant a solution but it’s completely portable. Never got into OneNote when I used to use Windows for the same reason.

I've been burned by 3rd party formats - never again - plain text for me.

You can export your notes as HTML, or better, .enex files. The latter are XML, with embedded stuff encoded with base64.