Some people don't understand the concept that while many people can do something, even do it well, it doesn't mean they can teach it well. Also as you say, competition fighting and self defense are different. In a ring you are facing off, there is almost a script as to how things work. Not specific moves but an initial progression. In a self defense scenario however the instigation of violence can be ridiculously varied.
As for the last I have pointed this out before. If competition in the Octagon or Ring is valid then so is Lei Tai (full contact competition) at Kuo Shu. I can agree that light points sparing might not be relevant. I firmly believe in the "train like you fight" method and if your experience is limited to light point sparing you can developed he habit of not going "all in", the problem rises when people assume that this is the limit of self-defense/traditional martial arts sparing, it's not.
Lei Tai at Kuo Shu is a knockout fest, especially during the qualifiers. In the free weapons fighting (sticks) I have watched protective gear get broken, even though the sticks have padding. Thing is some people search for rationalizations to attack other things, without the requisite knowledge, when they are trying to justify a preconceived belief that "their way" is the "right way."