The author defends the right to quit. Nowhere in this article does he state that it's a good thing to quit whatever you're doing once it becomes uncomfortable.
It's not because you have a right that it means you should use it all the time.
It's not because I have a right to free speech that I say everything that crosses my mind at the moment it does, with a megaphone in public places. However, not having that right would mean that when it is important for me to express myself, I wouldn't be allowed to.
Same goes with the right to quit.

As for alternatives, there's plenty. A.S. Neill came up with the Summerhill school in the UK in the 1920's. Attendance there is facultative. And it works fine.
You can also look up studies on "unschoolers" (kids who don't go to school and don't get formal lessons from their parents) all around the world, which prove to do fine as well. I'm sure Peter Gray can provide us with some research on that level (he has in his book Free to Learn).