Really feel like the article should also mention the problems this artificial selections causes on chickens themselves. I'm more familar with the broiler side than egg production, so I'll talk there specifically though know there are similar issues for chickens bread for high egg laying rates
The article doesn't mention the breeds of chickens these companies have created but some of the largest two are the Ross 308 and the Cobb 500. They are super fast growing and make up around 90% of all farmed broiler chickens. Their fast growth rates causes everything from mobility issues to worse immune response to disease. Here's just a handful of the problems:
The fast growth of the Cobb 500 is associated with an increased rate of various health problems. Compared to slower-growing chickens, they have a higher rate of sudden death syndrome,[12] hock burns,[13] Tibial dyschondroplasia,[14] weaker disease resistance and antibody response,[15] bone deformations, and problems with walking.[16]