In what way is any of what I said unrealistic? Its already been done. Many games have much higher standards than just one difficulty.

Difficulty settings can add a lot of extra development time.

Nonsense. This is one of the things that modders change most easily. Many of the things I want in difficulty settings are as simple as flipping a boolean.

I'm not saying difficulty settings that are robust are nothing, but you're pretending they take up way more effort than they do.