How do you figure, Robin? Though they do not fund the prize pool, WPA has responsibilities when it sanctions events. which are too numerous to list here, but some of the more obvious are:
1) WPA manages the world pool calendar. Did you know that when you get an event sanctioned, you get date protection from other events being sanctioned during that same time period? That's an enormous advantage from a marketing standpoint and it protects you from someone else trying to tempt the top players into playing in a competing event.
2) WPA has rules for entry that tend to obstruct those who wish to block diversified entry. It's member countries are all guaranteed invitations for its players, and that's important as WPA sanctioned events form the basis for a player's world ranking. The best players need to have equal access to a top world ranking, and WPA tries to ensure that they do.
3) WPA must collect and maintain results for use in the world rankings.
4) WPA must oversee potential substance abuse in its events.
Here on the AZB forum, WPA bashing is all too common, and there's no doubt that, in part, it is because Americans have so rarely played in WPA sanctioned events in recent years. This, no doubt, has made WPA less important to American players than others.
... but things are on the move. In the last six months alone, the addition of a) the Players Championship in Las Vegas, b) the International 9-ball in Chesapeake and the c) World 10-ball Championship in Las Vegas, to the American pool calendar will greatly change the level of American participation in WPA sanctioned events. Three new WPA sanctioned events in America is something we should all understand is a positive step forward.