> Suppose, for example, that a student’s top choice school is hugely popular. But their number two to five schools are only slightly short on places. Then it could make sense to register for the number two school in the first round. They would have good chances to get into the second best school. Going for the number one choice is risky: if they don’t get in, they have no shot at any school in their top five anymore.

Why would not getting into the first-choice school affect the student's chance of getting into any of their top five schools? The article's earlier description of the Boston method makes it sound as though this wouldn't be the case.