People who rail against the unreliability of Internet sources can make it sound as if before the Net we lived in a golden age when texts had been checked and rechecked before publication, all footnoted and referenced, and could be relied upon for their authority. (Books! With a capital "B"!)
In fact, amongst the millions (billions?) of books and journals and pamphlets printed before and since the Net there are plenty of dodgy sources, and we've always had writers and publishers who are sloppy or ignorant or just barking mad. We've always had to question our sources, whether it's in a Book or at a website. As my History lecturer said in our first tutorial, over thirty years ago (and it wouldn't have been an original thought), "When you pick up a book, the first thing you ask is, 'Who wrote it?' "
One positive thing about the Net is that a glaring mistake at a website won't stay there for long, provided the site is responsive to feedback, is frequently updated and has a reasonable amount of traffic. At my website (which satisfies those criteria), if I make even a small typographical error in someone's name I'll often get an email within days of posting the page and it can be fixed within minutes. (I'll still check that the correction is valid. Even in the case of spelling a name it's not always straightforward.)
By contrast, I have music reference books on my shelves that having glaring mistakes, but they'll stay there until the next edition of the book is published. That's if the book goes to another edition, and if someone has contacted the writer. In the past, that meant writing a letter, with a stamp, to the publisher. At least now you might be able to track down an email address and contact the author quickly, but it's still a more complicated and drawn-out process than clicking the Contact button at a website.