The DOM in most rendered web sites is far removed from any HTML directly read or written by humans. People can use whatever markup language they want and know

The DOM in most rendered web sites is far removed from any HTML directly read or written by humans. People can use whatever markup language they want and know that if it compiles to MathML, it will render in any browser. LaTeX support was a really long shot to be standardized and implemented consistently across browsers. It's just too powerful. For LaTeX users, the only thing that MathML standardization changes is that MathML is now part of the target language that a LaTeX implementation compiles to. Maybe that will be useful; maybe not.