Nope. You are either missing the point, or simply spinning the Apple talking points.
It is in fact very likely that Gatekeeper is another step in creating an iOS walled garden on our desktops, where only apps approved by Apple will be allowed on our "stock" Macs.
And this is NOT a good thing.
I actually jumped to Android precisely because I got tired of jailbreaking my iPhones so that I can tether, or use them on TMobile (once I realized how much better/cheaper it is than AT&T).
I've been enjoying tethering on my iPhone in Canada for a long time. No jailbreaking required. Your example is a poor one because it has nothing to do with a walled software garden, but is a licensing issue with carriers. Same as your choice to use a different carrier.
Certified apps ARE a good thing, but you've found reasons to see it otherwise based on your own usage. Don't confuse it with being a bad thing for the general population, though.