You take some raw meat, not even necessarily very good meat, and run it through a meat grinder. You’ve got hamburger, and you can make a pretty delicious hamburger.

You take a cooked hamburger and run it through a meat grinder, and you’re getting something else, and if you try to make a new hamburger, it’s going to taste weird.

There’s not enough raw pulp going into the meat grinder for the latter entries.