Tubes or pipe?

Without trying to defend the clueless Senator Ted Stevens, I still have to ask: Why was it stupid for him to say the Internet is a “series of tubes” but it’s smart when people in the know call it a “bunch of pipes“? Huh? (Yeah, I know Doc says it’s not just pipes, it’s also a marketplace, which as we know means it’s also a conversation.) Here’s a map of all those pipes, btw. Looks like a big clusterfuck of tubes, actually, more than a “series.”