The direct answer is too complex to argue in a HN thread. "More healthcare" is a trade off. At some point real resources have to be taken from somewhere and put into healthcare. There is no limit to how many resources can be put into healthcare, so more healthcare means less of something else.

The premise of the question is that more=better, without acknowledging more=less of something else. The argument over what gets given up is exactly the political process, and that isn't going to be fun to rehash. People throw out "what if we trade off [thing I don't like]" and the whole argument becomes divorced from what will actually happen in the actual policy implementation.

The more productive response is to lay out the viewpoint, without delving in to the theoretical justifications. The view is pithy and might help a few people understand what the thinking is.

An answer to the question would be an example of a policy and an example of when said policy "really hurt and isolated a significant population"

It's pretty straightforward, everything else is frantic hand waving.