But why else

would it be said then? It is a context of 'if you don't won't to go my way or their way, then I guess you can go your own way'.

""Suit yourself" doesn't always have a context of argument or conflict, any more than "Do what you want" does. It can be said neutrally. One has to listen for the tone."

I don't think this is suitable to be used in agreement. By all means, listen to the tone.

"Hey, we're all going to the game. Want to come?"

"Sure great." "Suit yourself"

or "Would you like more steak?" Yummy "Suit yourself"

how about "I would rather date Mary than Beth." Me too, I think Mary is prettier. "Suit yourself"

"Suit yourself doesn't work in any of these examples - as given. Switch the response to one that disagrees and "suit yourself" works in each example.

Not so. Yes, it's probably more common these days to hear it used facetiously but there are plenty of instances in which it is used neutrally.

"We have swordfish or steak, so suit yourself!" "There are three bedrooms available in the cabin so you can suit yourself."

I don't understand "Suit yourself" as having to do mainly with situations of agreement or disagreement. It's said when offering someone a choice or clarifying that the choice belongs to that person, not to oneself. It's a lot like "Up to you" and not a lot like "Up yours."