The people who tell you not to trust Wikipedia aren't saying that you shouldn't use it at all. They're telling you not to stop there. That's exactly what they told us about encylopedias too.
If you're researching a new topic, Wikipedia is a great place for an initial overview. If you actually care about facts, you should double check claims independently. That means following their sources until you get to primary sources.
If you've ever done this exercise it becomes obvious why you shouldn't trust Wikipedia. Some sources are dead links, some are not publicly accessible and many aren't primary sources. In egregious cases the "sources" are just opinion pieces.
For example there were pages that would state that "Scholars agree that the gospel of ____ was not written by _____ but was written by an anonymous author" when the original sources never discredited the original claim of authorship, but were essentially "I can't be sure who wrote it", never actually saying/discrediting that it wasn't written by said evangelist.
I think the anonymous perspective belongs there, but when the original source says "I cannot be sure who wrote it" then that's not saying it wasn't written by them.
Just look in this thread. I'm not talking about writing college papers. I'm talking about the boomers saying you can't trust anything you read on the internet.
Anecdotal, but I've never had a teacher tell me why Wikipedia wasn't a good source. Similarly, I've never had a teacher educate students on how to properly use resources like Wikipedia as a starting point for sources. All my peers and I heard was "Wikipedia is bad, never use it, it's not reliable, don't trust anything from it."
I wish I had been taught why and how earlier, but I had to learn why and how myself.