People may also just find that they don't get a lot of value from it, but if that were the only reason I'd expect geekforgeeks to rank equally high with it or higher.
It, however, has a long, well-earned reputation from being likely the worst site on the net for a decade, back in the early days. Even if I have a question that I think it would answer well, I still recoil at the thought of clicking a link to it.
For another example, I gather that most of the high school chemistry I learnt is wrong, but it was mostly pretty useful in understanding the physical world as far as I needed to progress in my education at that age. W3Schools can be useful in that respect.
Some lies are actually better than the truth. My favorite example is that shooters are taught to imagine their sights being in line with their gun and that's they're shooting horizontally. But they're not, they're shooting in an arc so over short distances bullet just rises a little. Don't ask why. Why it's cool is that people using this model are better shots.
I've used it for looking up SQL, XML/XSD/XPath and such when I had some specific question. Found it quite helpful, and still use it as a quick reference every now and then.
Nowadays with AI slop websites all over the place, plus formerly legitimate newspapers not attributing sources & edits either, this may not seem that special. But w3schools earned their reputation when that was exceptionally rude. Also, straight up wrong all over the place. But that is more of a symptom. And to be fair a lot of the software back then was straight up wrong, too. Tough job documenting the reality of the WWW correctly while IE was around.