I've used both for a decade or more, and my opinion is that includes/partials is the only thing AsciiDoc offers that even justifies considering it as a markup language for docs. If (big if!) using includes/partials without React is so important you'd consider giving up all the benefits of Markdown.
IBM, Microsoft and Stripe all have tooling that enables Markdown includes/partials. None of those will render natively in GitHub or Gitlab - but if you really need that feature you probably don't care as the AsciiDoc support is also so poor.
I think if AsciiDoc and Markdown were in the same league from a writing and reading perspective, AsciiDoc might have more traction. Other comments in this thread support the case that it's just harder to write and read as markup.
A whole other topic is how Markdown has been adopted by React-driven systems. This just solidifies Markdown's position as the lingua franca.
IBM, Microsoft and Stripe all have tooling that enables Markdown includes/partials. None of those will render natively in GitHub or Gitlab - but if you really need that feature you probably don't care as the AsciiDoc support is also so poor.
I think if AsciiDoc and Markdown were in the same league from a writing and reading perspective, AsciiDoc might have more traction. Other comments in this thread support the case that it's just harder to write and read as markup.
A whole other topic is how Markdown has been adopted by React-driven systems. This just solidifies Markdown's position as the lingua franca.