Boston is the American Dream writ large, a genuine meritocracy*. Meeting the
qualifying time** merely allows you to apply, and the faster runners in each age group are given priority. It is fair to say that North American long-distance runners are somewhat obsessed with Boston as a result. Just being able to apply, let alone getting an actual place, is a marker of your being jolly good at running.
*unless you get a 'partner' place (sponsors, charidees, etc..)
**which you have to run on a pukka marathon, none of this self-certified gps bollox.