Why McDonalds doesn't serve breakfast all day

I am subscribed to an amazing daily newsletter called "Now I Know" which is emailed to me every weekday morning. It's written by a guy named Dan Lewis (you can subscribe to it here if you want; you won't regret it.)

Anyway, the bonus fact in today's newsletter was really interesting. (The article was about Waffle Houses.) This is what it said:

Bonus fact: Waffle Houses serve breakfast all day.  McDonalds does not -- they stop serving breakfast foods at about 11 A.M., depending on individual franchises.  Why? Because the breakfast foods cook at a lower grill temperature than the regular burgers-and-sandwiches (but not hot dogs) menu; once the grill is turned up, breakfast can no longer be prepared.

I've always wondered this, because I always want an Egg McMuffin whenever I go to McDonalds. Granted, I only go to McDonalds maybe once a year, but whatever.