Markdown would need a better specification then. Today we have a number of extended implementations, want even more extensions and most of the implementations won't even handle the trailing double space (soft line break) the way it is meant to.

But indeed I'd love Markdown or something like that (AFAIK AsciiDoc is better) to be everywhere.

I actually evangelize Markdown on daily basis encouraging everybody to use Typora instead of MS/Libre Office in every case when there is no practical reason to use the latter.

My biggest regret is that Google Drive not only does not seem to natively support plain text editing, it seems to go out of the way to make it harder. I wish it could be more like Dropbox.