Tailgating is something I had long misunderstood and perhaps still do. Before I drank at all, I was mystified by people drinking themselves into a stupor and stumbling into an event. It was and still is all the more peculiar when you are going to a sporting event you have shelled out good money for. Why anyone would want to pay $100 to go to a football game drunk and not remember what happened is beyond me. They are fraud fans.
If tailgating is your event, fine. I think its perfectly reasonable to drink before a concert because
A. It's not that important to me
B. Concert's generally consist of standing around and listening to music not played as well as on a CD.
I am not a major music fan, so for me drinking before a concert isn't a big deal. People who tailgate and get wasted before games are generally not major fans of the teams they are watching. The drinking may even be the only reason they are there. I suppose I just get frustrated seeing people falling over themselves drunk. It's really only funny after the bars are closed, not at 4 PM. If you are going to drunk at a sporting event you should do your best not to annoy those around you who care about the result.
Let me make it clear that having a drink or two before the game is fine. I generally do not do it unless I am at a soccer game because I want to entertain my guest and get them buzzed to sing and chant. If you get hammered before a game you care about your a jackass.