This is getting downvoted because it's ludicrous. Users want WYSIWIG - documents that are what appears on the printer page or when people they share the document to open it.
"Interoperability" is something technical enthusiasts talk about and not something that users creating documents care about outside of the people they share with seeing exactly what was created.
as you say, tech enthusiasts only _talk_ about interoperability, but very very few actually care about it. Try interoperating between two pieces of code written in two different languages without spinning up an HTTP server or a separate virtual machine with a database system. Not even two different languages, just between two major versions of the same damn programming language.
I think you're missing the point that the "G" in WYSIWIG is "when printed". Everybody wants uniform rendering across applications in the way that, say, websites render uniformly across browsers. But fewer people care today what it looks like when printed--they're never going to print it anyway. They're just going to docusign it and call it a day.
In other words, fidelity to the printed page isn't really as important or as magical today as it was in 1984.
No, the G is "get". Users want to create documents in their presentation format. When they create a table they want to see a table, not a bunch of pipes and plus signs. When they create a hyperlink they want to see the link text, not the URL and a bunch of brackets.
Yes, the markup is hidden and the document is rendered in all cases. The point I was making, and I believe the parent was making, is that it doesn't have to be wed to the physical medium. Perhaps we're talking past each other here.
Writing markdown is decidedly not WYSIWIG. Storing documents with a WYSIWIG editor in a markdown-like format isn't viable either - look how frustrated word processor users get if changing one element repositions another ("all my pictures move"). Users want things in a precise format.
Nobody is proposing that people will be writing markdown by hand in text editors. Just that a lot of the complexity of rendering stuff on the screen precisely as it would be printed on, say, A4 paper can perhaps soon be left behind. People print a lot less these days, and thus WYSIWYG (in the original 70s, 80s and early 90s sense of the term https://en.wikipedia.org/wiki/WYSIWYG) may be less important.
"Interoperability" is something technical enthusiasts talk about and not something that users creating documents care about outside of the people they share with seeing exactly what was created.