@Wish. Look at the number of players in those sports. Total slalom skiers in the nation with a ranking score in b1 thru b3 is 313 skiers. And you want to break that up into smaller segments? Based on that, I would hope that golf and tennis would have age groups every six months to get a 100 per age group average that water skiers have. Look at it this way. Little Johnny has a 1 in 100 chance to win nationals. Give me any other sport that has that kind of odds. The odds get even better in the trick and jump events. Unfortunately, the sport we all love just does not have the numbers to support that many age groups. Many may say that we have too many now based on the number of skiers. That's what allows a trick skier who skies on two skis tied together ski at nationals. (that's a whole different mess)
The great thing about this sport, is that you can set individual goals. You ski against your PB. With the exception of regionals and nationals, it does not matter where you place. I always told mine, that if he skied above his seed, then it was a good performance at regionals and nationals.
Are you putting to much emphasis on winning? You say no, but your posts always come back to that. There are ways to enjoy the sport without the pressure of winning. Part of the enjoyment of nationals, is getting to see the friendships that develop of kids from all over the country. Yes, the first year going from g2 to g3 will be tough, but if the passion for the sport is really there, your skier will work thru it.