That's always the first thought that occurs to me. Any standard or tool that wants to render mathematical notation has to seamlessly interact with and accurate

That's always the first thought that occurs to me. Any standard or tool that wants to render mathematical notation has to seamlessly interact with and accurately render AMS LaTeX. Without that, working mathematicians simply won't use it. And TeX in maths is absolutely not going anywhere. MathJax gets this, so MathJax has been successful.