I am not in favor of ESI. However, the article (and comments so far) did not acknowledge a huge problem with Medicare for all, which is there are lots of employees with (what they consider to be) very good health care coverage which is likely to be (even if just perceived to be) better than Medicare. For them, change is a hard sell.
It's true that a some members of powerful unions have negotiated better health coverage in exchange for giving up pay and other benefits. Those are commonly known as "Cadillac plans". However, it would be wrong to deprive the rest of the population of health care just for that minority. Adjustments can be made in the law to recognize those Cadillac plans.
And, you will not (1) ever suffer bankruptcy due to medical expenses. (2) have any added medical costs such as those for co-pays, prescriptions, , or needed tests or procedures.
And no wait for insurance approval to have tests that your doctor thinks you need. And doctor doesn't have to call and justify your treatment to insurance companies.