Interesting. I have most of this and various toolchains installed as standard on my work boxes, so for me, for instance, to get a preview pain in Atom, I just added 2 packages and the Atom module and it worked. For Pandoc, even less -- I just installed Pandoc and bingo, I could convert to/from.

I feel sure that there must be some happy medium somewhere between the skeletal marked-up text formats of RST, ADoc and Markdown and the excessive complexity of (say) DocBook, but I don't know what it is, and if it exists, it might not be FOSS.

I used to do a lot of writing and editing for Wikipedia (before someone unjustly accused me of vandalism, and a couple of my bigger pieces were deleted -- after that, sod them, I just do minor copy-edits) and I was happier with MediaWiki markup, but I guess it's not very intuitive.

The professional FOSS documentation tools I've worked with are at one extreme -- the "Docs as Code" philosophy that holds that embracing programmers' tools such as Git and various programmers' editors mean getting a lot of power for little investment.

https://www.docslikecode.com/

The other extreme are powerful proprietary tools, often on Windows, such as MadCap Flare, which I haven't worked with.

I reckon there is space in the middle for something like Wikipedia with versioning and branches, but nobody's inclined to invest in the R&D. There are tools, they work, so why should they?