In the example I mentioned, I may sometimes choose to put a small dictionary initialization into a single line if it's just a detail, or may split it into multiple lines if it's important enough for someone reading the code to pay attention to it before going further.
This simply cannot be decided by an automatic formatter without it knowing the code's purpose which, for now, requires a human brain.
Someone mentioned elsewhere that automatic formatters remove the cognitive load of formatting code, but I argue that load is an intrinsic part of programming, because it is (for the most part) the effort of communicating to the next person that comes along.