Why suggest that headlines should have enough detail to prevent people from reading the article and gaining a fuller understanding of the material? The problem isn't that headlines don't have enough details, it's that people want to or already do treat them like the full story and never have to learn anything nuanced therein.
The purpose of a headline, at least in an ideal world, is to tell you whether the article's topic is relevant to your interests. That's all that's being asked for here. Being able to properly parse the headline is a good start.
If it did say "band concert", that would still be grammatically dubious but would still indeed be more self explanatory. But it literally doesn't say that.
