Someone once told me you can't understand US politics without understanding Linear Algebra.

End of the day each party needs certain to appease certain people in certain locations. Like any marketing team they segment their "customer" i.e. voter base[1], then rationalize actions to get there post hoc.

The general public depending on the news channel they wire their head into will have the same opinions.

Hence, it will unlikely to get a sensible answer by asking this in a forum. The actual answer is behind the scenes from political operatives who do the literal political calculus.

PS [1]: this is one reason identity politics is so appealing to them as it's logistically easy as it maps well to their customer segments

I'm not disagreeing that cable news broadcasts a lot of propaganda, but you can't both claim that you're servicing "customer" segments based on calculus, and also claim that the news wire viewers into the same opinion.

If it's the latter you don't need the former, etc.

I can agree that shoddy news (a lot of it these days) do abuse viewers worst instincts and provide plausible coverage for it, but there is clearly something more going on for a sustainable amount of people to still support this.