I wouldn't ever mark up documents like that. JSON and XML are shitty languages for such things. So is html to be honest but we're stuck with it.

Markdown, rst or something are better. As long as it has a simple deterministic terse grammar that is... If you want you can stuff that inside XML or rst and attach metadata.

That was the point. Markdown too has its weakness: it doesn't scale very well - how do I markup chemical symbols, or gene names, or complex tables? We soon run out of keyboard symbols to denote many concepts...

i agree. I think We should create and use extensible languages (both written and spoken) that are better represented and understood both machine and human.

Mathematics, English and most notations are too full of nuances to represent things unambiguously.