Fair, I've updated my post. I'd argue it's not just FPTP presidential systems, though. Even in proportional representation you still only get one vote so you pick the candidate that's the best fit for you, you still don't get to pick and choose which parts of their agenda get enacted.
Yes, but different people will care more or less about different things and thus vote for different parties which all have to work together to form coalitions, which in theory then have to reflect a negotiated compromise among the different things that different people care about.
It’s not perfectly efficient, and it can suffer from the problem you’re describing, but far less severely than the US system does.
