Thing is - it works. Both online and in-person. I'd much rather be honest about how little I know (and often am when I'm working long-term with someone), but I've found it's a losing strategy in most situations. If you do know your stuff, you'll just get shouted down by idiots. Better to shout the idiots down first and then do the research to make sure you're not wrong. If you screw up everything, you'll probably get another chance simply by virtue of confidence (look at John Meriweather, who nearly brought down the global financial system three times and is still managing money), but if you appear timid and then screw up, people are all like "I knew he didn't really know what he was talking about..."