mb386, at least the dude or dudette made it to the last hole and kept you company. You know you can always go back and finish the hole(s) when they quit on you. Worse when they quit after few holes and you're stuck alone, but that's life.
Many reasons people would quit. If for average, the logic is you get credits when turn amateur, pro, and likely master (when lower your average). And with the credits you can get new clubs, win tournaments, maybe trips, or win...wow...I think I convinced myself to quit more! Just kiddin'...No need to explain further. Or maybe the dude or dudette just had to take a crap!
Anyway, who cares if they quit ultimately?, have fun