Here’s a (very stupid) parody of the attitude as I imagine it from the most obstinate people with this view:

Well, my doctor says I need to take this medication, so that's what I'm going to do. I don't care what all those other people online are saying about their experiences with it. My doctor knows best, and I'm not going to listen to a bunch of anonymous strangers on the internet. They're probably just making stuff up anyway.

Sure, I get that a lot of people had some nasty side effects or didn't see any improvement, but my doctor assured me that won't happen to me. He's a professional, so I trust him completely. And I know he's only trying to help, not line his own pockets or anything.

All those online forums and support groups are just a waste of time. What could a bunch of regular people possibly know that my highly educated, experienced doctor doesn't? I'm going to take this medication exactly as prescribed and not ask any questions. My doctor is infallible, and I refuse to get a second opinion or consider any other options. Nope, I'm just going to blindly follow his advice and ignore everyone else. That's the smart and responsible thing to do!

(Yes, this is extraordinary (and like I said stupid), and yes your doctor knows more than JoeRando420 telling you to buy homeopathic crystal suppositories. In fact I only have one user in mind writing this post, someone I forget who posted long ago about a condition I cannot remember. Hope they got better.)

Main point is: why not let a large number of people who heard about a condition from their own qualified doctors help you at least scribble down some questions to ask your own medical folks at your next appointment? (But please avoid those crystal suppositories.)

Edit: thanks everybody, read all your posts and they're all great points! Glad I posted here. Thanks for reading something at least 80% dumb :)