One possible weakness of a constituency system
Alexis de Tocqueville wrote in Democracy in America that democracies are weak when it comes to foreign policy. The Senate's failure to hold Secretary of State Hillary Clinton and President Barack Obama himself accountable for the Benghazi disaster is a case in point. But the Clinton hearing, and the confirmation hearing of her successor, Sen. John Kerry (D-MA), the day after, revealed an additional weakness of our system.
Proponents of a parliamentary, proportional system or representation, as opposed to our winner-takes-all constituency system, argue (correctly) that parliamentary systems do a better job of representing political minorities. The advantage of our constituency-based system is that representatives are directly accountable to the people, not to distant party bosses--at least in theory, and certainly more so than in parliamentary models.
But constituency-based systems seem to do a poor job when they must defend the legislative branch as a whole against an onslaught from the executive. That is especially the case when the head of government is not chosen by the legislature. There are simply too many divided interests to present a united front except in rare cases.
In interviewing Clinton, for example, the Senate Foreign Relations Committee would have been far more effective if it had chosen a few Senators to lead questioning, rather than chopping up the opportunities among the different Senators, each of whom only had a short period of time to speak. There was little time to develop lines of questioning that led anywhere--and the Senators, eager to place their remarks on the record for public consumption back home, wasted much of their time bloviating instead of confronting the Secretary of State.
There was a need for united opposition precisely because the administration has defied the Senate--most vividly in Clinton's outburst: "What difference does it make?" She should have been rebuked for that, and should not have been allowed to escape Sen. Ron Johnson's line of question, but the microphone simply passed to another Senator shortly thereafter. We do not need (nor should we want) proportional representation, but better coordination among legislators would go a long way toward reducing an inherent vulnerability.