In general, either will be simple as long as your input is simple, and they will become complex as soon as you want something complex — I am pretty sure people here bringing the pitchforks are really not even aware of how reST looks like in the first place.
But looking through examples at https://docutils.sourceforge.io/docs/user/rst/quickref.html#..., I really see a lot of non-simple stuff done in an obvious way too (block quotes, tables, bullet and enumerated lists, sections and headings, separator lines...).
By the time you got on the markdown train, it has already won out, and you've probably seen a lot more of it than of reST, even if MD still wasn't standardized. As a counter-point, having done lots of reST with Python docutils prior to 2010, I still mix up reST and MD — there's nothing intuitive about any of their special syntax, and our perception is mostly tainted with our prior experience. I've also written a lot of ASCII-only docs prior to either of those, and most people used ever-so-slightly different conventions there as well (somebody mentioned using /this/ for italics as well).
reST was standardized in the form of a Python PEP from its inception so you could at least rely on learning it once.
Edit: My ultimate point is that you (and most everybody else, including me) are using MD because it's more popular, not because it's "better".
I'm not arguing one is better, just that Markdown is simpler: it literally has less syntax. If I don't need all the bells and whistles of reST, Markdown is simpler to learn, use and likely implement.
I agree that reST is probably a better fit for complex use cases like building a docs site. But it's overkill for Facebook Messenger or even forum posts, IMO.
If you want to use a mark-up language in a chat app, a subset of either would serve you just fine and both are equally simple. It sounds like you are comparing a subset of what-is-markdown-today (and there are still variants) to full reST, which I don't think is a fair comparison.
From a very brief look, here's some things that probably aren't generally necessary (and aren't included in Markdown): Document structure, Bibliographic fields, complex footnotes and citations, directives, substitution definitions
All of these increase the number of things I have to escape, as well as my cognitive load when writing documents. And that's before we talk about reST config settings!
You could use a subset of reST, or you could just use Markdown!
But looking through examples at https://docutils.sourceforge.io/docs/user/rst/quickref.html#..., I really see a lot of non-simple stuff done in an obvious way too (block quotes, tables, bullet and enumerated lists, sections and headings, separator lines...).
By the time you got on the markdown train, it has already won out, and you've probably seen a lot more of it than of reST, even if MD still wasn't standardized. As a counter-point, having done lots of reST with Python docutils prior to 2010, I still mix up reST and MD — there's nothing intuitive about any of their special syntax, and our perception is mostly tainted with our prior experience. I've also written a lot of ASCII-only docs prior to either of those, and most people used ever-so-slightly different conventions there as well (somebody mentioned using /this/ for italics as well).
reST was standardized in the form of a Python PEP from its inception so you could at least rely on learning it once.
Edit: My ultimate point is that you (and most everybody else, including me) are using MD because it's more popular, not because it's "better".