The vast majority of people don't do pullups with a dead hang, even if they claim they do. They often go into an active hang 1" above a dead hang. Go over to the bodyweight fitness subreddit and it's littered with dudes who could 10–15 "pull ups." Then they learn they can do only 3 or 4 with a full ROM.
There isn’t that much strength difference between full ROM and an inch off of it. The scapular flexion at the bottom lifting you up from the dead hang actually gives you momentum that helps counter some of the challenge. You do need to be used to the full ROM movement and shouldn’t expect to just pick it up on demand during a test.
To break the world record for one mile of lunges, you need to be used to the same sort of high ROM movement.
There IS a world record for it somewhere. Much slower than the record for actually running a mile, of course.
These "dead hangers" are brain dead if they think their fitness goal is best served by doing the hardest pullup possible.