[not_knuth]

I didn't think of that. It makes me think that my question is just a more specific case of: "Why do some applications converge on standard file formats?"

I.e. Why are PNG, JPEG, HTML and SVG ubiquitous, but not ODF?

You gave some reasons for why document editing didn't converge on ODF, DOCX etc., but I wonder if there are some common factors that could let you look at a potential application standardization opportunity and decide if there's a chance it will happen or it's best to let it be...

[Someone]

Partly it’s commoditization (https://en.m.wikipedia.org/wiki/Commoditization). There’s no money in differentiation of image formats (in part because browsers dictate what formats people can view, but also because the current set is good enough for typical use cases). Note taking apps seem to think there is in note taking.

Partly it’s not true. Tools such as Photoshop have their own image format. You could even claim PDF is the format we converged on for exchanging rich text data.

[taubek]

ODF and DOCX are at "war". DOCX claims to be open, but it's not everyone cup of tea. I personally like it.