I can certainly see why the League would protect its members from having to compete with teams that do not follow the same recruitment, attendance, and practice rules as League teams. Still, invitational tournaments are, by definition, well--by invitation. Schools choose who they want to invite, and schools choose whether they wish to attend and compete with the other schools invited. If teams CHOOSE to invite another team for competition in an invitational tournament, what is the League protecting us from?
Also, as previously noted, League schools are allowed to CHOOSE to compete with a variety of other types of teams who obviously do not follow the same rules of recruiting, practice, etc. as League teams...so there must be another issue at work here.