The Men's coat

While studying the video series I came up with a question about adding length to the coat front facing "below the button". I can understand how adding length and width above the button gives the facing enough fabric so the lapel can roll beautifully.

But my darn curious mind keeps asking about the length added below the button. I can see where the 5/8" swing out will help give ease up to the roll line and lapel when it pivots back. But I can not understanding what the extra 3/8" inch length down does. Why doesn't this cause the facing to droop or sag on the inside? Or even cause the facing to push down on the bottom of the coat front on the inside making it flare out instead of in towards the body?

I figure there is a logical answer but all my thinking can't reason it out.

Thank you, Roy