Do earlier Black Friday hours really affect the bottom line?

I've not heard of a store that said their business was positively impacted and they made more money because they opened a few hours earlier. Seriously, the "doorbuster" deals always sell out in the first 10 minutes anyway, whether they are offered midnight Friday, the Thursday prior, or 7am Friday. I liked it better when 7am on Friday was the opening hour of the shopping season, and feel really sorry for the employees who have to work during their Thanksgiving dinner hour.

But seriously...does it have that much of an impact, and why?