The largest perception problem with the ACA is that it is "something separate"

This discussion of the ACA centered upon "keep it" or "throw it away" involves a distorted perception that it is a "thing" which is independent, like a playground ball. It isn't. It is nothing other than the regulatory requirements of what must go into a health insurance policy.

No one has a conceptual difficulty with a state law requirement that everyone must have automobile liability insurance and that an automobile liability policy must have a minimum amount of coverage, like $15,000. Those requirements are accepted as nothing other than minimum requirements. The ACA is of the same species.

What the ACA does is specify several mandatory elements of health insurance policies, no preexisting conditions, coverage on parents' policy, minimum service coverage. Since these elements increase the cost of the policy, the ACA includes a requirement that everyone who is able purchase a policy, thereby increasing the risk pool to offset the costs. Other means of reducing the financial impact to insurers includes subsidies for policy cost and expansion of Medicaid to remove low income, high risk folks from the private market.

You can't "repeal" the ACA without redefining the minimum requirements for inclusion in a health insurance policy. If you eliminate all minimum requirements, than what is available and the cost will be in the sole discretion of the insurance companies, who have a mandate to return the most benefit to their shareholders. That will obviously mean reduced coverage elements at higher cost, and restrictions on availability of coverage in any manner the insurance companies want, be it preexisting condition exclusion, risk exclusion, lifestyle exclusion, etc.

So "repeal" means no standards, which will mean significant retraction in the markets.

Just keep in mind exactly what the ACA is and the fact that it isn't a "thing" which can be kept or thrown out.