Not mostly, mostly consumer preferences. You wouldn’t be able to sell them and it’d just be wasteful

In this case it’s because if you raised them no-one would want to buy them. The egg laying breeds are a lot tougher and have a lot less meet than the ones bred for meat. They also cost more per amount of meat in the end.

The simple fact is that people don’t want to buy that, so it’d just be wasteful to grow them out.