I disagree. The reason a lot of newbies start with W3Schools is because they're the plague of Google search results. Popularity isn't everything. If it was, we'd all be promoting Nicki Minaj as the definitive source of quality music.

That may be why they start, but nobody would come back if the site wasn't so terribly useful, concise and easy to navigate.

The people who are using W3Schools are, almost by definition, the kinds of people who don't know that the site has glaring errors, and can't spot when the page they're looking at is wrong.

Imagine if you were using a calculator to help calculate dimensions for a house. But unknown to you, 1 in 20 calculations you make came out with an answer that was 10% out. Is that calculator useful because 95% of the time you get the correct answer, much faster than you could have found it yourself?

Nobody ever navigate in w3schools, they come back from Google each time.