Before the 12th amendment, the presidential candidate who got the second most electoral votes became the vice president. This meant they were usually different parties.
It occurred to me that one thing this achieved was always ensuring that there was someone in the room who would be willing to disagree with the president. He couldn’t surround himself with yes-men.
That’s how it works now with extra steps. The system doesn’t provide any defense when people are working as a party regardless of their branch.
It’s the extra steps that are the point though, right? It’s harder to get control of the presidency, Senate, and House than just controlling one of those.