Should HS boys throw the 16 pound SP from Day One?

This post was going to be about the weight events, of which there are only two indoors, the Weight Throw and the Shot Put, with all the attendant records and names and possibilities for the new indoor season.
And I will get to that.  (It's only December 14th--have patience!)
But in thinking of the stats, I got to thinking of, shall I say, more WEIGHTY matters.  (Heh!)
As in, the actual weights of the shot ball itself.
I'm more into running, but I've been around T&F long enough to know the records, and the weights used.
In international  events, the men's SP weighs 16 pounds (7.26 kilograms), while the women's shot weighs 8.8 pounds, or 4 kilograms.
In fact, the female weight doesn't change, as it's the same weight from high school on....in college, and in the professional ranks.
However, the men's weight DOES change after high school!
While high school boys DO throw a 16 pounder from time to time, the main weight for them is 12 pounds.
I believe the only times boys throw the heavier weight is in post-season championship meets, and if they compete in "adult" meets in the "open" division.

Why?

Why do HS boys throw the 12 pounder, when as soon as they leave the HS ranks, they will NEVER throw that weight shot again....at least not in NCAA or USATF or IAAF events?

I don't see why boys can't throw the 16 pounder from freshman year on.
To my mind, the 12 pound shot (or any of the other "junior" weights used around the world--see Jacko Gill's records in 3 or 4...or is it 5 or 6...different weight categories!!) is equivalent to training wheels on a bicycle.

When a kid learns to ride a bike, dad or mom tacks on training wheels to help create some balance while the kid learns to balance him or herself atop this new vehicle.
Once they get situated, the training wheels are removed, and the rider is on his or her way to the Tour de France!!

What good does using the 12 pounder in HS do?
Coaches might say that a kid's body isn't fully developed at age 14 or 15 (or even 16 or 17) to be able to handle the heavier weight.
Not enough muscle, or something.

I'm not a physiologist or an anatomist or in the medical field, and I've never been an official coach,  but it makes more sense to me to have the kids throw the same weight shot they're GOING to throw once they're in college, or turn pro.
As soon as they start college training, the 12 pounder is GONE!!
(Do college coaches use it in training their new guys?)

Even though the distances would be less than they are now, the new putter would get used to throwing the 16 BEFORE entering college.
The way it is now, it forces the athlete to start over from scratch while adjusting to the heavier weight.
Four pounds difference isn't much to a guy weighing over 200 pounds, but I'm sure there must be SOME alterations needed in making the switch-over.

So eliminate the switch-over.
Use the "training wheels" shot, the 12 pounder....IF YOU MUST.....in fall & winter training ONLY!!
Once the freshman has started to learn the technique, and adjusted himself to holding a big ORB next to his neck, then those "training wheels" can be removed and stored away!!

Meanwhile, the frosh SP'er will toss the "adult" ball, and be on his way to Olympic glory!!

The current indoor HSR for the 16 pounder is:

63-11    Ryan Crouser       2011

(The outdoor 16 pound record is Michael Carter's 67-9, achieved the same year--1979-- he threw the 12 over 81 feet!!)

The girls throw the same weight throughout their career!
Why not the boys??