Title text: The heartfelt tune it plays is CC licensed, and you can get it from my seed on JoinDiaspora.net whenever that project gets going.
Transcript
2003:
[Cueball approaches a bearded fellow.]
Cueball: Did you get my essay?
Bearded Fellow: Yeah, it was good! But it was a .doc; You should really use a more open-
Cueball: Give it a rest already. Maybe we just want to live our lives and use software that works, not get wrapped up in your stupid nerd turf wars.
Bearded Fellow: I just want people to care about the infrastructures we're building and who-
Cueball: No, you just want to feel smugly superior. You have no sense of perspective and are probably autistic.
2010:
Cueball: Oh my God! We handed control of our social world to Facebook and they're DOING EVIL STUFF!
Bearded Fellow: Do you see this?
[Inset, the bearded fellow rubs his index and middle fingers against his thumb.]
Bearded Fellow: It's the world's tiniest open-source violin.
Most environments will correctly format a Markdown document without any trouble now if sending it to a co-editor.
If it needs to be tamper resistant, it's easily converted to PDF.
What's not especially easy, today, is adding advanced styling (like a watermark) to Markdown, since Markdown itself has no provision for it. I accomplish that through a connected CSS file, but that's a bit of an advanced move.
See, that's the issue that PDF serves due to its ubiquity. You say "environments" like my mother can pull up a markdown version of a recipe and print it out. Tons of stuff gets sent to people who have no idea what markdown is or how to open it in an appropriate reader. Windows, for example, doesn't know how to open a .md file, even if the recipient could figure out why they got a zip file with a bunch of randomly (or specifically) labeled parts. Edge will render a PDF in a default windows installation and Safari will do the same in a default OSX install (IIRC); no zips, no extra files, all neatly packed into one.
It's usually not ideal for communication between people with experience in whatever field is being discussed. I'd rather get a plan in DWG format if it's a building design, or in Word if it's a written document I'll need to edit or reformat. With the exception of an exclusively-text document like an ebook that I'd like to re-flow to a myriad of devices, PDF is the digital form which is the most universal for anything I would previously have requested in dead tree format.
Your mother really can open and print a Markdown file now. It has come that far.
But I totally agree with your core point. The gulf between "most environments" and "everywhere" is still a big deal.
That said, for those who hate creating PDF files, I know of a great pure text format that converts very nicely to PDF.