I do this pretty often, and it's often a very valuable exercise, even though I'm almost always wrong. Interrogating the apparent contradiction between my beliefs and existing reality is a highly fruitful learning experience. There are several serious failure modes, though:
1. I can get my ego so wrapped up in my own idea that, even once I have the necessary information to see that it's wrong, I still don't abandon it. In fact, this always happens to some extent; when I change my mind it's always embarrassing in retrospect how blind I was. But the phenomenon can be more or less extreme.
2. In a context where posturing to appear smart and competent is demanded, such as marketing, advocating totally stupid ideas puts me at a disadvantage, even if I recant later. Maybe especially then, because it reminds people who might have forgotten.
3. People who know even less than I do about a subject may be misled by my wrong ideas.
4. This approach is most productive when people who know more than I do about a subject are kind enough to take the time to explain why my ideas are wrong. This happens surprisingly often, both because people are often kind and because the people who know the most about a subject are generally very interested in it, which means they like to talk about it. Still, attention of experts is a valuable, limited resource.
5. People who know more than I do about a subject can get angry and defensive when I question something they said about it, particularly if they're mediocre and insecure. The really top people never act this way, in my experience; if they pay attention at all, either they can explain immediately why I'm wrong, as AlotOfReading did here (though I may not understand!) or they go "Hmm, now that's interesting," before figuring out why I'm wrong. (Or, occasionally, not.) But people with a good working understanding of a field may know I'm wrong without knowing why. And there are always enormously more of those in any field than really top people.
So, I try to do as much of the process as possible in my own notebook rather than on permanently archived public message boards. The worst is when group #3 and #5 start arguing with each other, producing lots of heat but no light.
My theory about why the angry and defensive people in group #5 are never the top people is that they stopped learning when they reached a minimal level of competence, because their ego became so attached to their image of competence that they stopped being able to recognize when they were wrong about things, so they are limited by whatever mistaken beliefs they still had when they reached that level. But maybe I'm just projecting from my own past experience :)