There are certainly problems that can and will arise when using long-handed gear with small children, such as lacrosse sticks or hockey sticks. There is a risk involved when kids, who haven't had the chance to fine tune their motor skills, play with long-handed implements. Chances are, they will end up accidentally hitting each other in the head.
However, I don't believe that they run a risk of hurting each other because they are so young. That is just a common link. Focus needs to shift to their motor development. It is completely possible to be young and have the necessary motor skills to handle a lacrosse stick. There certainly needs to be a gradual progression of development before anyone can handle one. The basics must be observed first.
Children have the ability to mature earlier than usual. I believe that they have the ability to meet realistic standards that you set for them with the right education.
Here is a video of a 7-year-old boy named Luke who is already an amazing tap dancer. I originally saw him perform as a guest on So You Think You Can Dance, but could not locate that video. I was lucky enough to locate this one. Luke proves that while he has undoubtedly been gifted, a child does have the capacity to learn faster than what normal standards tell us. Whether this is because he enjoyed what he was doing and was thus determined to work hard at it or not, he still had the ability. This shows us that kids can rise to a challenge. Maybe they just need to be interested in what they are doing.