I think it's erroneous to think someone who demands a 6'3 guy won't settle for someone shorter. Those "requirements" as listed on a dating profile are about as strict as "5 years experience with a framework that was released 4 years ago" on a job posting. They're an ideal, There aren't enough men in the world to meet the "6'-6'3" requirement and the majority of would-be partners will have to settle.