Triggered by your "modern format" comment, if my sleuthing is correct, the mdoc format was first introduced with "4.4BSD" from 1995, with a major update in the early 2000s', whereas HTML was first conceptualized in the 80's with a first major release in the early 90's; mdoc IS the modern format.

Granted, it may not be the ideal format for documentation, but I'd argue neither is HTML - too much cruft for reading in a terminal and not very ergonomic to type out. I'd argue markdown or something like that would be a better fit, it's got support for the formatting and linking needed, most developers are familiar enough with it, you don't actually need to parse or render it to be able to read it, etc.

Well I read man pages Via debians web server precisely because they are easier to read in html.

https://manpages.debian.org/bookworm/manpages-dev/syslog.3.e...

Bit I don't think html would be a good source format.

Relevant: Compiled HTML Help (1997) https://en.wikipedia.org/wiki/Microsoft_Compiled_HTML_Help

Try HTML version:

  man --html=firefox man