How should burger patties be prepared in terms of mixing and flavourings?
Neither is right nor wrong, it simply depends on what you are trying to accomplish.

The way I make a basic burger is to try and pull off the right amount of ground meat from the package and shape it right there as is without kneading it at all. Literally just enough handling to shape it.

However sometimes I want a seasoned burger, and that's more like making a patty shaped meatball and you can't really avoid mixing/kneading it in the case.

Sometimes seasoning the outside of the burger is all that's needed.