Your example
Imagine telling fire insurance companies that they had to sell policies to people whose houses were already on fire, and then pay off on them. How much do you think fire insurance would cost in a couple of years?
Imagine an insurance company telling the fire dept to let a home burn down to the ground because the homeowner didn't sign one form correctly.
You are actually against reforming the "no pre-existing condition" requirement? You should care more for the sick and less for the fat cat insurance execs.