WEIGHT CLASS VS. AGE

Austin had his first football game yesterday and it brought up some issues. One being : should we go by age or weight limit when playing football. Reason I'm asking is because the team they played from Virginia had two players that were well over 200pounds. Parents had their birth certificates with them to prove that they were only 10.
Now... I have grown up on football and have a good understanding of the game. However, it has been a learning experience for me watching Austin go thru practices, putting on football gear (yuck)and dealing with the many strains, swelling, etc.. that go with the game. Contact sport indeed! So... seeing these guys yesterday made me think that we would be in the hospital at some time that day.. but luckily Austin made out o.k.
So the question remains.. should they go by age and have players like yesterday destroy another team? Or go by weight limit? Weight limit would have some players in a higher age group and sometimes these kids don't get to play because they don't have the experience (because they don't get to play). Seems like there should be a happy medium... but it's one or the other. After yesterday I'm leaning more with the weight limit. Even though this most likely would leave out the really skinny kids and the overweight kids. Yes, they can go to a higher age limit but how much play time would they really get? Jeff would be a good person to answer this question with all his experience with football and coaching. I'm thinking there isn't an easy answer.
Luckily, Austin wasn't injured in the game (as many were). The team lost I believe 21 to 0. Although Austin said it was 35 to 0. He could be right as I went to the concession stand for a little bit. But what a mess of a game. Like throwing lambs to the lions. Either it makes you tougher or you get injured trying.