Maybe in W3C specification MathML is a part of HTML5 and browsers will not crash when there is MathML inside (actually they also do not crash with custom tags)

Maybe in W3C specification MathML is a part of HTML5 and browsers will not crash when there is MathML inside (actually they also do not crash with custom tags) but many libs are not supporting the MathML tags or respecting them or working with them. Just one quick example... JQuery and open this in Chrome http://sdiehl.github.io/jquery-mathml/ http://sdiehl.github.io/jquery-mathml/ So for the Chrome and Safari guys MathML is already dead and it even has flaws in Firefox. But what is written in W3C documents is not always the truth out there or common in the WWW ;) So yes I agree... rip MathML out of HTML5 specification.