#2: Yes, this point is ignored because it was not really the focus. The benefit you speak of can be realized without statements like "W3SCHOOLS IS TROUBLE" in big scary letters on W3Fool's homepage. The attitudes of the people involved and the clarity of their content are the focus of the article.
#2: OP misses the point of why there is so much hostility. If W3Schools was on page 3 for (chosen utterly at random)"getElementById" on Google, no one would care. Predictably, however, it's number 1. That's pretty dire - I would hope that the top results for common questions would be quality resources. Which W3Schools is not. There is a greater good here, which is not served by continuing to promote W3Schools the top developer resource.
#2: getElementById returns developer.mozilla.org as the first result for me. Anyway, what about the point of why there is so much support? Convenience beats accuracy. I don't use W3Schools much now because I know of the inaccuracies, but I loved it as a beginner since not many sources I found were as intuitive as it.