Imagine that. Treating all listeners as equal instead of putting them into arbitrary demo boxes. Naturally this was presented as a negative.
Stations don't have "demo boxes". Advertisers do.
So success and survival require that commercial stations attempt to appeal to the ages and other criteria that advertisers use to buy ads.
That means picking a hopefully large subset of the public advertisers want to reach and doing a good job attracting them.
Some people like country, some like hip hop. Generally, people who like certain music styles do not care for or even hate other music styles. So stations can't treat all listeners as equal... because they aren't equal.