Reddit, Stack Overflow, GitHub/BitBucket (readmes, tickets, wikis), and it's also used by a couple of CMSs, blog platforms, and static website generators.

Virtually all of the text I write is Markdown. Even this very comment is written in a subset of Markdown (and so is yours).

Yes and notice how few have used it even here. Most replies are plain text.

Paragraphs and emphasis are frequently used here.

paragraphs are plain text :)

No, they are not. It's not directly spit into an element with white-space: pre-line or white-space: pre.

It's converted into paragraphs. Just like stuff inside asterisks is converted into emphasis.

sigh. plain text paragraphs cant be claimed to be invented by markdown. sorry. good try tho.

Invented? You are missing the point.

The comments are written in a markup language (Markdown, UBB, whatever...) which is then converted to HTML.

It's transformed and not displayed as-is.

Thats like saying BP invented oil. To claim a plaintext only comment, sans markdown syntax, as markdown is a big stretch to make. But I understand you will want to make that stretch inorder to justify the magic utility of the format. Thats a big whatever from me.

Anyway. Im not going to argue this further. Agreed to disagree.