This is a misstep and is a very British, very parliamentarian way of looking at democracy, which is dominated by party politics. Politicians aren't as interested in the needs and desires of their constituents as a whole, just the ones aligned with their party.
In American politics on the other hand it was all about voting for an individual politician who they believed would advance the interests of their state or district, the national outlook was irrelevant so long as politician advanced the general outlook of the voters over the party.
Look up the history of a senator named Strom Thurmond. He changed party affiliations at least three times in his career but his first priority was his home state of South Carolina, eventually getting two interstate highways and a major army base built there.