A database that would enable anyone to identify opportunities to dance which are local to them, that just happens to have national coverage, could be quite useful.
Useful to whom?
Let's say that I knew that I was going to travel to Kansas City, for example, for a week. I would want to see if any studios are convenient to my hotel and what their class offerings might be.
In the first place, I can already do so. We have a tool of national coverage - worldwide coverage, in fact - known as the Internet. With only a little effort I can locate studios in Kansas City and pull up THEIR websites for up to date information.
Secondly, as you point out, such aggregative lists are difficult and costly to maintain. BDC has a list of studios which is pretty good but still incomplete and slightly out-of-date. A list of classes at those studios would be much more dynamic and correspondingly more demanding of maintenance. Accordingly, the costs of supporting such a site would have to be passed on to the users. Why would people pay a fee for something when they can do better for free?
So please explain to me how pointing out some obvious truths about this proposal is "unfair."
jj