My experience says the opposite. Sorry.
I made websites sporadically from '97-'03 and then started again in Dec '11. My criticism of w3schools is from my personal experience with the site over the last year.
I was surprised when I found out that w3schools actually intends to teach people html/css. Until recently, I thought it was universally acknowledged that they're a content farm.
Google downgraded w3schools in search. It used to be constently the first result. Now it is rather 5th or 6th.
I too had the exact opposite experience. I found the HTML, CSS, and Javascript tutorials extremely intuitive and well-presented when I was in 7th grade. I ate them up.
Yes, some people find it useful when they don't know better, but I suspect those people at that point they would have found almost any tutorial useful.
Let's look the page for explaining 'div': http://www.w3schools.com/tags/tag_div.asp
"The <div> tag defines a division or a section in an HTML document.
The <div> tag is used to group block-elements to format them with styles."
Oh, I get it. Its for grouping block-elements(??) to format them with styles(??).
The above is followed by this fantastic tip: "Tip: The <div> element is very often used together with CSS, to layout a web page."
Looking at their "examples" its an in-browser html editor with un-annotated code that makes a table suitable for the web circa 1995.
Then it trails off in to sparse definitions of the attributes for the div tag with an excessive amount of discussion about web standards compatibility.
Normally I wouldn't gripe about an awful tutorial site but w3schools consistently ranks high in google queries for questions about html tags. Personally I've never left w3schools with an answer to the question that led me there. That signals to me that it is indeed a failure.