That is one of those claims that is both true and absurd at the same time. When this country entered WWII, we were in no shape to take on Hitler. It took a couple of years to build to that point. Likewise, had Saddam been stronger, we would have had to engage in a year-long military buildup to take him on. But the end result would have been the same. Since we didn't need a buildup (despite the claims of the armchair generals to the contrary), we didn't need to go the WWII route of a protracted buildup and a year-long pitched battle to get to the enemy's capital.
That's what happens when you apply the lessons of the past without adequately evaluating the present - you get to sound authoritative and stupid simultaneously.