How Do You Bake if You're High?

For the past several years, many products come with high altitude baking directions - usually it has you add more flour or cook for a little longer. What I have noticed, however is that these directions have the altitude listed for which they are applicable, and it is usually 3500-6500 ft. What I am wondering is, why the limit? What about people who live at higher elevations than 6500 ft? I for one live at 6700 ft, just out of range, so I figure I can get away with following directions for 6500, but what about the people in Leadville, CO which is over 10,000 ft? Are they supposed to figure it out by themselves? Or maybe, the high altitude directions are only for that particular range, and any higher or lower you can just use the regular directions. I doubt it. Basically, what I am saying is that the range is stupid - give us a lower limit for when the high altitude directions apply and leave the upper end open.
*By the way, in case you are in doubt of my intelligence, obviously all of these questions are sarcastic and meant to point out how the instructions are flawed. Of course, there are probably people out there who will need clarification for these types of things - you know, the ones who need safety warnings like "do not iron clothes while wearing" or "remove child before folding stroller." Here is a site that has more funny instructions.