Truth be told, the most compelling reason for carts is so golf can be played everywhere. I know many courses that simply should not be played without one [yes, I know some of you madmen could, but why WOULD you?]. People who do not live in flat lands SHOULD still be able to have courses to play ..... period.
Reality intrudes again! For most of golf history, people with wealth, who mostly live in flatlands and waterway cities. Then, as money spread to the farmlands and outcountry, golf courses flowed and rolled. Now even we mountain rednecks occasionally want to spend a few bucks for golf. Again, yes, you MIGHT survive a walking round at ER, Hidden Cove etc ...... but why would you try?
Doug