The reason you put breadcrumbs in meatloaf is so that the meatloaf binds together and doesn't fall apart.
The breadcrumbs in meatloaf also help add texture to the meatloaf and makes the meatloaf taste better and holds it together.
If you don't use breadcrumbs in the meatloaf it won't come out as good and will fall apart.
You need to add eggs and breadcrumbs which work to bind the meatloaf together.
You can also use crackers and mayonnaise in the meatloaf if you have no eggs or breadcrumbs but have mayonnaise and crackers.
I tried making meatloaf without eggs and breadcrumbs or crackers and mayonnaise to bind the meatloaf together and it was okay to eat but it fell apart when I cut it and wasn't as tasty.
So now I use eggs and breadcrumbs so that the meatloaf turns out properly.