See you aren't getting it. To the students that are going to go drink and party nothing has changed. That is the problem it is still going to be VEISHA to them.So let's say you and your sibling are taken to the park by your mom. You're all having fun and playing, but your sibling is being a brat, throwing fits and breaking playground equiptment. Is your mom just going to leave you there while taking your sibling home to punish them? Or are you going to have to go with even though you were behaving yourself? Often in life, everyone gets punished because others are misbehaving. Same as in sports. When I played, the whole team ran when one person did something stupid.
And I think it will prevent things. Off the top of my head, I can't think of all too many student riots in Ames outside of VEISHA.
To your analogy though it is different like I said. I don't think there will necessarily be a riot this year but in your case the problem is stopped by punishing both kids. In the VEISHA issue it really won't prevent anything.