I've been using the internet since 1994, so I think I'm a bit of an expert on what it's like to use the internet (yes, I'm being ironic).

What has always jumped out at me, and I've been the perpetrator in the past myself, is that an awful lot of guys have as their actual hobby reading about a hobby on an online forum (was newsgroups before that) and then repeating what they've read as if it's their own experience talking. I call these guys "internet experts" because the only place that they actually seem to know anything is when they are typing on their keyboards. In real life, they are imbeciles.
So on the examples mentioned above about Edge 540s and Cubs- it's very easy to find out on RCU that these are not beginner planes. There are many threads on both where a pilot got a big surprise that cost him a crash and many more where pilots complain that they just can't get the hang of flying these planes. So the internet expert sees that, and now he knows to tell forum newbies to stay away from those planes because they are hard to fly. He's never flown them himself, but that doesn't matter.

If a guy is going to use an online forum for his primary source of information, he needs to read very broadly and evaluate his sources. We have to keep in mind that every single post on RCU was written by someone who took the time to do it for free. The most knowledgeable people don't educate for free, so it's frequently the blind leading the blind on here.