This has a few advantages. One is that voters can choose the candidate they like most, knowing their vote can still matter even if their favorite politician loses. Another is that voters would no longer have to live in the small fraction of swing districts for their votes to matter. Parties would have to compete for all voters, everywhere. But the third and most important advantage of a system like this is that it makes third parties viable, as unlike under our winner-take-all election rules, a party that gets 22 percent of the vote can get 22 percent of the seats, rather than nothing at all.
