I never really liked these types of guidelines. They don't consider practice sessions and the ability of each kid as being unique. Practice session frequency and intensity have a major impact on endurance and pitch count thresholds. Are we only going to track game pitches and pretend every pitch thrown in bullpens or those in warm-up don't count? That's craziness, but that's exactly what seems to be happening with youth pitchers.
If a kid only throws in games and does nothing on the side, then he will not be capable of throwing as many pitches in a game as a kid who plays in one game and throws two bullpens in that same cycle. Putting the same pitch count limitation on both of these kids is ridiculous.
Some kids get tired or sore after only 75 pitches that all have a hump in them and would be physically incapable of more. Pitch limits exist to protect that kid with no plan, no routine, and no conditioning.
My son throws approximately 200 pitches per week with no lingering soreness or fatigue, has never had an arm injury, and he throws harder than anyone in his age group in his league that consists of 14 teams. He throws a baseball in some capacity 5-6 days per week. If that means 1 game and 2 bullpens or 2 games and one bullpen, or three bullpens (never 3 games). It's all due to his established routine.