As a matter of fact, yes, I do. Do I believe a P3 is 1 second faster per kilometer than a round tubed bike? Absolutely. How about 2 seconds? And more, according to some of the studies I've seen, depending on the speed of the rider.

So, over a 44k course he loses 88 seconds.

In which case "big difference" needs definition. Is there a big difference between winning and not? Some might answer yes.

Apply that TT time loss to the grand tours, not to mention time lost in the mountains because of a heavier frame that doesn't transmit power as well, and the steel frame riders don't win.

Folks this is pro racing we're talking about, not a Sunday club ride. The manufacturers are going to put their best riders on the equipment they think will give them the best chance to win. Wishing steel was competitive doesn't make it so, but neither does it mean steel isn't a perfectly good frame material for other cycling pursuits.