a. No matter how you think it works, the publishing industry doesn't work the way you think it does. This is true even for publishing professionals. They know how their part of the industry works, and they know a lot about adjacent areas, but the further afield they go, the less reliable their expertise will be. People who aren't in the industry generally don't have a clue.
i. A phenomenal number of articles about how publishing works are written by people who don't know what they're talking about. This is partly because writing about writing, or writing about publishing, is what wanna-be authors do when they've given up on writing, but don't yet want to admit it. It's also because a made-up version of the publishing industry is going to be much simpler and more logical than the real thing, and thus is easier to write about.
ii. Look askance at articles that credit some industry practice to the stupidity of people working in the industry, who have failed to see the simple and obvious solution the author of the article is about to suggest.
3. There are easily as many scam agents, useless agents, and clueless agents as there are real ones. They all swap bad information with each other. The difference is that the scammers know it's bad information.
a. You can't research this subject just by getting online and looking. You have to stick to good sources.
4. Did I mention that any idiot can write a book about how to be a writer? When you see someone who's never sold a book, but who's written a book about how to get your book published, and said book was published by a vanity house, and said author is nevertheless accepted as an authority on the subject by a great many aspiring writers, you know you've wandered into strange territory.
a. The scary part is that I've just described more than one Authoritative Source of Advice about Writing and Publishing.
b. Any idiot can put up a website, too.
c. Check out your source's credentials.
i. It's always worth your while to assess the quality of the info you're getting, because bad advice can cost you such an inordinate amount of time and effort.