Yeah having caught up on the thread, what this is telling me is that a lot of people just don't understand basic sampling statistics.Some of these comments have a real, “statistics, how do they work?” kind of vibe going on.
The entire point of statistical sample theory is that once you capture a certain number of people, you can confidently use those results to apply to the greater whole, even if that whole is much much much MUCH larger than the sample. The numbers that WOTC has are not only a good sample, they are an AMAZING one. Like this is the kind of survey results all pollsters dream of.
Now...the trick is, polling a representative sample of your audience, and that's a question mark. Obviously wotc is going to have a bias in online people who take their survey, or whatever demographics visit their site. Those are potential issues you could poke out the survey and say "this might be a problem".
But the actual number of surveys, oh no that is a wonderful number, way more than WOTC needs to confidentially project results.