No not at all but even the most responsible, level headed teen has been known to do an act of stupidity every once in a while. I love to think that my son (17) is a mature, level headed adult but the fact of the matter he often does things that make me shake my head. and I know for a fact because I'm the advisor who has to sit in the office when the "oh so responsible college student" gets rip roaring drunk after a eagles game.
So yeah, go to any college campus and you will see more than enough proof to realize that yes they do some how lose their commons sense.
So since I can't control what any teen may or maynot decide to do at any particular moment, it's simply easier for me not to have alcohol at a party.
I'd be more concerned with the 40 year old adult who can't come to a barbeque and not survive without a beer for 6 hours.
I guess thats the difference, you have the opinion that the OPs party is like some party on a College campus, and I have the opinion that its a backyard BBQ where alcohol is served. The first example, a party TO get drunk at, and the latter, just a party, where even a college kid could control themself in the face of a cooler full of Mike's.