Insurance shouldn’t cover preexisting conditions. If it did, its not insurance but Welfare. Imagine if insurance cover car/house insurance after it burn down
(I didn't quote the "burning house" part because it has become an annoying cliché).
Maybe insurance shouldn't cover pre-existing conditions but why should a pre-existing condition prevent a person from obtaining health insurance for unrelated medical problems, which was the previous system? Why not just exclude the pre-existing condition?