Probably because they're on the 250 for the first two or three years.
What he's getting at is that even a 250 has capabilities far beyond what a novice (under 2-3 years of consistent riding) can utilize. No shortage of stories of highly experienced riders on small CC sportbikes eating the lunch of inexperienced riders on supersports on the track. Yeah, they'll run away on the straights...but anyone can go fast on a motorcycle in a straight line - that doesn't demonstrate skill.