No knocks taken. Your comment just sparked some thoughts. I agree with your point about the cheerleading. It's fun, and necessary. Satire is an effective tool too.
On the subject of fiat, maybe "by definition" is a bit strong - but "arbitrary decree" appears more accurate than "mandate." Disregarding that, it just seems that a proper interpretation of what constitutes "fiat" comes down to intrinsic value.
Paper cash became accepted because it could also be spent. Gold used to be accepted, now it isn't. Most don't even recognize it anymore, not beyond "shiny yellow metal." Bitcoin, although different in essence, won't get a free pass on the challenges we've faced before. People (and our underlying psychology) are still involved, even if the system changes.