Some pretty big advantages: They are voting blocs that are long lived enough for reputation to work. It makes representatives much easier to follow and predict (for media and citizens). They become much more efficient in wielding power and less vulnerable to divide-and-conquer adversaries.<p>Relatively few people can keep track of what a handful of parties did in the last couple of years, imagine how short the public memory would be if it was single representatives.<p>&lt;cue comments suggesting technological solutions&gt;<p>Also, ideas in politics are interrelated. A big core value or strategic objective will pretty naturally lead to a bunch of other related ideas. You can view this as &quot;buying into political beliefs wholesale&quot; but it&#x27;s a pretty natural thing to happen.