If a single person gets the majority of votes, then they get to make the decisions.
But there would be multiple constituencies in my hypothetical scenario. Someone from the Left Party in District A gets a majority of the District A votes, but someone from the Right Party from District B gets a majority of the District B votes. So, the majorities in Districts A and B get their voices effectively represented, but the minorities aren’t shut out. In District C, no one wins a majority, but all the voters are represented in the legislature.
Compare the current system, where the Left Party in District A gets the majority of votes (or even the most votes, but no majority). The Left Party wins District A, but there’s no representation at all for the voters who didn’t vote for the Left Party. Isn’t it easier to buy the vote of just the one Left Rep for District A?