I'm not sure where you are going with that, but if you think you're going to convince millions of people to rewrite their websites because $NEW_TECH is now on the market, think again.
He is politely giving an example of a superior mark-up language. Just because developers are effectively forced to eat shit we shouldn't pretend it's a piece of a nice cake. Things like angu-bootstrap-whatever are just a thin layer of icing on the top of a big pile of manure.
That's not what parent is saying. Parent is claiming that the only thing preventing us from welcoming our new XAML overlord is that it's made by Microsoft and not an "open source" project made by "some hippie group of developers". That's hogwash.
It's hogwash because nobody is going to invest billions to remake the Internet with a non-backward compatible technology, wherever said technology comes from.