Rules FAQ
Rule Misc.
One Ball Condition
Q. What does the "One Ball Condition" mean?
A. The Rules of Golf
do not require a player to use the same brand and type of golf ball
throughout the stipulated round. A player may use a different ball to
start each hole. However, the Committee may adopt as a Condition of a
Competition, the "One Ball Condition." When this condition is adopted,
players are required to use the same brand and type of golf ball
throughout the stipulated round. Please refer to Appendix 1; Part C; 1
(Specification of the Ball).
Basically WGT has adopted a somewhat modified version of this USGA rule, which typically is used in tourney play with professionals and high level amatuers. Under this rule should you run out of the same ball mid match you would be DQd and unable to post a score. WGT just replaces you with the starter ball so you can finish the round which I suppose is better than having your round end and being WD if it is a single play ready go or match play.
As Icon says its been this way forever and unlikely they will change it. When you have 1 ball left you are given option to by more or just make sure you got enough of that ball before round starts or don't use it.
This issue has been brought up so many times i can't even remember. Try searching the forums first, chances are if you thought of it or have a complaint about it, somebody else has already beaten you to the punch