The thing with responses like "do a weight check" is that you're often offshore, on a boat, with people waiting around. You can do a rough weight check, but if you sit around checking from 20# all the way down to 6# a pound at a time, people around you are going to be mad. Ballpark recommendations are very valuable for not wasting people's time.
So? You're paying for the dive? Tough
Not taking the time to do weightchecks and diving over weighted leads to accidents.