I think most tournament directors attempt to adhere to the guidelines regarding weight classes. However, I would bet there are tournaments on any given weekend violating the maximum weight allowance when combining weight groups.
Something interesting has come to my attention while reading that area of the constitution though. That being, even the suggestion of a 6U age group could be considered to be unconstitutional since all of the allowable age groups are directly addressed. The result could be, that if a tournament even offers a 6U age division at a tournament their tournament charter could be ruled null and void. The exception could be that the lowest age group recognized is in fact an 8 AND under, however this might be something we need to address in constitution and bylaw changes.