We might like to think this is true, but it's absolutely not. David v Goliath is great if David wins, but most of the time it's Goliath with a comfortable 2-0 without even trying. Look at the FA Cup finals since the famous Wimbledon win. I'd count a dozen where there's a big club against a 'smaller' one. The only David to win was Wigan.
What you're saying doesn't really make sense anyway. First, they're concerned about viewing figures so they make sure the big teams go through. Then many people will simply switch off if it's only the big sides left? How can both be right?
Still, everyone seems to have been bored to death by the Barca game tonight