This is true. But then again, as I've said before, a good GM can make just about ANY game system work, no matter how badly it's done.
However, this does not absolve the game developer from maintaining and correcting issues with their product!
How many, say, software companies would stay in business if they became known for habitually not fixing bugs and errors in their programs?
Individuals and small groups might not have run into problems. But when you look at the user community as a whole, certain arguments crop up again and again. Regardless of which side you are on in any particular argument, the fact that they do keep happening indicates that something there is unclear enough that a good number of people ARE having a problem with it.
To come back to my analogy, a computer program can have a bug that some people never run into or don't really notice. That does not mean it's not there, or that nobody else has a problem with it.
It is understandable that a game book can and will have problems that were not caught in production and playtesting. It is impossible to make a perfect game, at least not out of the gate. But that is what errata is for. You identify issues that the user base is having with your product, and you take timely steps to address the issue. Just because your customers can impose their own fixes does not mean you shouldn't go ahead and work out and release official fixes yourself.
Proofreading corrections are nice and all, don't get me wrong, but they are not errata.
-k