Yeah but your argument ignores the fact that this all has to be hashed out after the fact. Before this ruling, presidents could ask counsel if something was legal or not (ex: there are tapes of Trump doing this during his attempt to steal the election) and they could answer based on statutes and case law. Now the answer always has to be "depends on what judge we get, there are no precedents". Jackson makes this argument in her dissent, and I think she's right that this is a sea change in the relationship between the US and its president.