You're right, sufficient exercise and knowing that you're the boss would solve 99% of problem with most dogs I reckon. Lets face it though, if everyone who has a border collie, lab, spaniel etc. were made to get rid of it if they didn't/couldn't give it enough exercise there would only be the workers and a small handful of pets that would be left.
For me, having a dog is all about having a fit, healthy and happy dog, it's great seeing them running around and looking good. I can't imagine having a big fat lab that can't even run, I just don't see what pleasure anyone would get out of that