Why would you use markdown to take notes? Markdown is designed to be displayed as rich-text (headings, lists, etc) after authoring. If you only ever view it in plaintext as an editor, what's the point?
The syntax is easy to type, it's not verbose, and it actually makes sense in plaintext. Then if I ever want to I have the option to open it in a full-fledged markdown viewer, and sometimes I even copy/paste sections into actual markdown-compatible apps.
It provides a standard method of plain text note organization. If I want to create a list or a subheading, I now do it the same way every time, so I'm internally consistent with all my notes.
In fact, for certain types of greyhairs like myself, it is extremely readable in source because it is based on the conventions people used in Internet forums that didn't support rick text.
BBS's, Newsgroups, all of the social "networks" adopted a core set of syntaxes that people still use today, such as _emphasis_.
The history behind that is interesting. We started with underlines to suggest emphasis because that was something you could do on a physical typewriter: Back up and add underscores to what you'd already typed.
When typesetting arrived, we switched to italic because it's way easier to read. But _emphasis_ stayed as a way to suggest _underline_, even if we prefer to render it as italics.
There are similar stories behind other formatting choices, like
> Some quoted text
The overriding design goal for Markdown’s formatting syntax is to make it as readable as possible. The idea is that a Markdown-formatted document should be publishable as-is, as plain text, without looking like it’s been marked up with tags or formatting instructions.
Perhaps this is a silly reason, but I use vim and I like my markdown syntax highlighting. I rather like reading my plaintext markdown + (default) syntax highlighting. I suppose it would be possible to write/use some txt syntax+highlighting (or some .note format, etc.), but I reinvent the wheel in enough other places to not want to do that here.
It's markdown compatible so you write in markdown and the text is automatically formatted while you type. It's really clever fix for the problem you are describing
Even if you only did view them as plaintext, it sure is a handy format for a static blog generator in case you'd like to turn some of your notes into a blog post one day.
I'm sure there are a few more markdown "WYSIWYM" I'm forgetting...
To build your own see also https://simplemde.com/. Basically CodeMirror is friendly to mixed-font syntax highlighting.
Also yours truly https://mathdown.net
Yes, I do in fact use Orgzly. For a very specific subset of notes it's fine. But for a long bit of documentation, no good editor exists on anything but a desktop / laptop. That is, nobody's reimplemented enough of Emacs on Android yet.
"Long bit of documentation"? Isn't it the device that's not suited? I sure wouldn't want to do a lot of typing on a handheld device. Emacs shortcuts should be fun.
Don't get me wrong, I love org mode, but there is no real support on Android other that a damn-fine list-making app that uses a subset of org-mode format for its lists.
For typing, Termux's "extra keys row" makes ctrl and meta combinations possible with your favorite keyboard: https://wiki.termux.com/wiki/Touch_Keyboard
...or you can just use Hacker's Keyboard (but I find it too cramped).
Git also runs fine under termux if that's what you use to sync your org file.