Exactly the point.

Bread crumbs, carrots, onions, even celery. All filler elements to make the meatloaf taste better and go further.

It's a WW2 meal designed to make rationed meat go further.

How is that recipe not just a giant baked burger?

We used corn flakes, 3 eggs (had chickens, have them now too), Worcestershire, onions, and maybe celery, mixing it by hand was good fun to me for some reason. As an adult when I started growing mushrooms, I added a bunch from a flush that produced way too many to use and was starting to go bad, and omg I love it that way now! (Not necessarily mushrooms on the edge of going bad, but is a good way to use a lot up and freeze for later meals!)

It's also there so the proteins from the meat don't all bind together and turn your meatloaf into a meatbrick.

When you have 6lbs of meat you don't need filler.

My mom (and consequently, so do I now) would use quick oats instead of bread crumbs. Add in an egg, onion, green pepper, maybe celery. Now it's sounding really good, haven't made this in a while, thinking I'll have to do that this weekend.