HTML and CSS are free to use but the W3C is funded by membership fees.
BTW I'm of the opinion that frontend tooling developers should actually try to contribute things to HTML and CSS instead of building "component libraries" on top of them.
If the native controls were good and if the browsers allowed using "uniformly styled" versions of them then there would be no good reason for such libraries to exist.
I have been on HN since 2008, his comment is by far the worst encounter ever in my memory. The sense of entitlement, not only in one comment by literally every single one of them in this thread and despite all the explanation he still believes he is right.
And to top it off he manage to drag HTML and CSS standards into it.