FWIW, this is also one of the reasons MathML has never become the "input" language for mathematics, and the layout-focused (La)TeX remains the de-facto standard.
Ergonomics of input are important because they increase chances of it being correct, and you can usually still keep it strict and semantic enough (eg. LaTeX is less layout-focused than Plain TeX)
MathML is used a lot in standards/publishing, such as with JATS and EPUB. MathML is also natively supported in the HTML specification.
But there, as with any DSL, you are trading-off ease of expression with ease of processing (e.g. interiperability). Every embedded DSL, XML included, chooses some amount of ease of processing.