People here really tend to keep their chickens very pure so there’s a lot of inbreeding.
Hmm, not sure I completely agree with this statement. Here, very few people are interested in keeping their breeds pure. They just want meat and eggs, so they breed anything to anything. The amount of unhealthy birds produced is tragic. If one breed/line has one problem, and you mix it with another breed/line that has another problem, you'll get chicks that have no problems, but you'll also get chicks that have one problem, and chicks that have both. Carefully outcrossing is beneficial, but just throwing outcrossing out there isn't really fair