Scott, you are missing the point. The warranty's may read the same, but the required conditions are different.
i.e. Motor OEMs recommend 50::1 gas/oil mix using a TCW-III rated oil, and base their warranty on that fuel. So OEMs ask for a specific oil at a specific ratio. Have you seen them recommend Amsoil at 100::1?
Amsoil recommends 100::1 gas/oil mix with a non TCW-III approved oil. They warrant that their oil will not be defective, but have written the warranty such that if their oil is non-defective (very likely), and your engine fails, and the OEM won't fix it (very bloody likely), they may choose to fix it, or not choose to fix it.
You may obviously run your motor anyway you want, as you accept the risks. However, a lot of people depend on the advice in this forum, and to advise folks to run non-recommended fuel ratios and/or non-approved oil is irresponsible, IMHO.