Medicare for all is veterinary medicine for humans. The owner of a dog chooses whether to pay for a treatment or not. No one asks a cat if she wants to be put down. In medicare for all, the government is the owner.
I'm pretty sure no one is going to put you down without your permission.
A health care system run by the government doesn't care if you are happy or not. It's the government. You are out of options. If the government thinks some treatment is too expensive you will die.
How is that any different than what an insurance company does? Except an insurance company actually has a profit motive the government doesn't - to pay big dividends to shareholders and executives.
When employees are unhappy with the choice of health care plans the employer finds another insurance company. It's called competition and the government doesn't have it.
The keyword being the EMPLOYER would find another insurance company. You think your employer cares whether or not you live or die? THey just get another one.
What I remember about Employer-provided health care, other than my two-year fight to actually get them to pay for my surgeries, was every year the HR Cow would get us all in a meeting and let us know it was open enrollment time, and how this year, the insurance would cost a little more and cover a little less.