Think about "Why text files won for programming source code."
Rich formats like Smalltalk's images are vastly superior as long as you stay within the ecosystem. But plain text is "worse is better" at scale. You get more tools, more interoperability, more of everything.
Markdown is the plain text file winner for uncomplicated words. It's somewhat portable between a myriad of tools. When you drop into a "Better" tool like OneNote, you get all sorts of amazing wins... Provided you stay within the walled garden it provides.
Speaking as an author, I blog in markdown, I take notes in markdown, and I publish my books from markdown source for this very reason.
Heck, being able to put my books in GitHub and do pull requests is enough reason all by itself!
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If you meant, "Why a tab instead of a separate app that works with Markdown," none of what I wrote above applies. I was speaking strictly to why Markdown instead of some proprietary-format notes app.
"Why a tab instead of a separate app that works with Markdown"
I'll bet the answer is similar: Everyone already has a browser open and quite a lot of notes are copy-n-pasted from other tabs. Availability, interoperability, etc.
Rich formats like Smalltalk's images are vastly superior as long as you stay within the ecosystem. But plain text is "worse is better" at scale. You get more tools, more interoperability, more of everything.
Markdown is the plain text file winner for uncomplicated words. It's somewhat portable between a myriad of tools. When you drop into a "Better" tool like OneNote, you get all sorts of amazing wins... Provided you stay within the walled garden it provides.
Speaking as an author, I blog in markdown, I take notes in markdown, and I publish my books from markdown source for this very reason.
Heck, being able to put my books in GitHub and do pull requests is enough reason all by itself!
---
If you meant, "Why a tab instead of a separate app that works with Markdown," none of what I wrote above applies. I was speaking strictly to why Markdown instead of some proprietary-format notes app.