I think it should be mandatory to learn about overstocking when keeping fish, you don't have to exercise that option. But everyone should learn about it.
There would be a lot less fish deaths if people's eyes were opened to these things instead of being sheltered from it.
I know for a fact that if I was taught earlier on about the principles of overstocking I would have been able to provide a healthier environment for my fish, even when it was understocked to now way overstocked.
And I am certain that's a rule of thumb that can apply to any new fish owner.
We all want the healthiest tanks possible for our fish and with a little bit of interest in overstocking you plant a seed of knowledge, in my experience that's only beneficial for everybody.