It suppose I can see "executive power should be part of the executive branch" as a facile argument because it does seem basic and a bit tautological, but it is still quite a strong point. It needs to be addressed rather than just identified and dismissed.
Except that's a bad summary of a bad argument. "Rulemaking" is what Congress is supposed to do.
I suppose in that case you are wholly opposed to the regulatory system as legislative power should be part of the legislative branch?