They’re the most common meat chicken, doesn’t mean they’re the best. My friend raised 7lb freedom rangers easily. I have raised both Cornish & freedom rangers in my 8 years of doing so, and I have seen the health of the Cornish vs FR and it’s a huge difference. With that being said, many people are trying to go back to the heritage breeds & not do production birds, like myself, and as fast growing as Cornish are, that’s why we don’t want to grow them. Your chickens that you raise yourself, despite being a breed that I personally don’t want to raise, are still so much healthier and happier than the ones in the stores, so I consider all of us lucky that we have the knack for raising our own meat like this