A friend of mine became a professional caddy,he was 6'6" and his stride was yard perfect.He use to caddy for top players like Raymond Floyd.He said his book of yardage's to the tour course's was so accurate he use to sell them to other caddys.
I think if you ban caddies then you have to maybe give the pros some other aid,like a measuring device.Caddies also help their player on the practice round before they play.Like how they are hitting the ball that day.How long they are hitting their irons etc.
I once watched Payne Stewart practice at St Andrews on the course range.He's caddy went through every driving hole,and Stewart hit the required drive for that hole,be it a fade or draw or whatever.The work detail that the caddy would have had to do to map Stewart around that course would have been enormous.There are bunkers every where, hidden from the tee.For players to do this themselve's would be impractical.
The game is hard enough.