We don’t need to speculate about how his proposal, such as it is, would work, because we’ve seen this movie; that’s exactly how health insurance worked before Obamacare went into effect in 2014, after which insurers were prevented from discriminating based on medical history. Under the pre-Obamacare system, insurers often refused to cover Americans with pre-existing health conditions or required that they pay very high premiums — which meant that they effectively denied health care, in many instances, those who needed it most.