I had this same question, I learned "meat" chickens are called broiler chickens, they were bred to put on weight rapidly. Egg laying chickens are separate breed and grow slower or won't grow to the size of a broiler. The industry is limited by containment footage, so they wouldn't use a male egg laying chick where they could house a broiler.
If a particular farm can produce 1000 kg of meat and 500kg of bones/other waste in a year by raising female meat chickens, would it be a waste to devote that farm to raising 500 kg of meat and 400 kg of bones from male egg chickens? In a sense, that's a waste of the farm to produce half as much meat as it can produce through killing chicks.
It's a philosophical difference on what weight to assign to the lives of chicks, adult chickens, other resources including human labor, etc. The lazy shortcut is to maximize return on dollar investment with no regard for any of those moral, ethical, and philosophical considerations, and that's what most of the industry does today, but even if you shift to a new moral framework you'll need to decide how to weight those things.
The industry kills them right away because they're not selectively breeded to grow as fast as broilers do. Egg laying chicken have been selectively bred to lay high quantities of eggs instead
Due to modern selective breeding, laying hen strains differ from meat production strains (broilers).
As an aside, in both cases, the selective breeding has led to all kinds of health issues for these birds. Broilers can hardly walk due to being fast-growing. Egg laying chickens have all kind of bone health problems due to producing lots of eggs (takes a lot of calcium to produce an egg shell)
They're totally different breed designed to lay as much eggs as physically possible compared to broilers that are designed to grow edible muscle as much and as fast as possible.
My dad has had pet chickens for decades, and his roosters always chill. They're highly intelligent animals. If you give them lots of vegetation and space and provide for their basic needs and well-being, they don't really get too aggressive.
There's no way socialism would provide that either on the scale that the Western world consumes chickens. We should still go vegan in a socialist economy.
Because we like big chicken breasts and we cannot lie.
(Male chickens of egg-laying breeds don't have as much meat, and also the males left together often compete and can try to kill each other. You'd want around a dozen hens per rooster, compared to roughly 1:1 that would come out naturally with eggs, and have enough space for each to call their own).