It has a pretty bad reputation from an earlier era when it was actively providing bad information [0]. That's largely been resolved from what I understand, but the reputation lives on.
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.
For what came up to me when searching for Python info before I blocked it, they still have plenty of incorrect information or information that's useless for the tutorial page it's on
This will be controversial, but w3schools isn't bad for the niche it targets today.
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.
It's targeting a different market. The MDN web docs are excellent reference material, but if you're learning or early in your career they're impenetrable. W3Schools has a reputation of over-simplification (to the point of being wrong sometimes), but that's not at odds with being useful to people at a particular stage in their career.
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.
Education is a series of smaller lies. It's one of the corollaries to "all models are, wrong some are useful."
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 w3schools a fair bit, but hardly for their web stuff.
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.
I haven't gone to that site in a long time, but back when I did work that was related to its content, it was somewhere between useless and actively bad. From reading this thread, it seems to have improved since, but it has a tarnished reputation. I use Kagi, and if w3schools had come up in a search I'd likely have set it to block before even considering clicking the link; it's got a tarnished reputation.
Content that kind of looks like technical docs, but without linking authoritative sources, date when it was last reviewed, software it was verified against etc.
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.
