To preserve more of the meat, I presume. If you gib a bird not much larger than your bolt with a big arrowhead, most of that meat is going to be cut to ribbons and difficult to properly butcher - especially if the bolt penetrates all the way through.
11 and 12 were created to prevent the birds from being damaged, but to what end? To keep them fresh longer?
To preserve more of the meat, I presume. If you gib a bird not much larger than your bolt with a big arrowhead, most of that meat is going to be cut to ribbons and difficult to properly butcher - especially if the bolt penetrates all the way through.
Small birds are usually served whole. It’s a lot less pretty with a huge hole
Feathers for decoration too probably