The problem is that there is a point that although the patient can be treated it isn't financially worth it to the insurer. If the insurer is under a contract they may be required to continue paying, although the less reputable companies will try to find a way to not pay. If the government is the insurer, then there is no such contractual guarantee - just try to get the official contract for Medicare.
And if the only legal source of payment under a single payer system is the government, you don't even have the legal right to say "I don't care what the government says, I want to pay for a hip replacement." You will have to either bribe a congressman or flee the country for treatment.
Jocelyn Elders was fired because she came out for death panels saying that young people were going to be funding Social Security while old people are just gonna die anyways.
The Stalinsts can’t handle the public being told the truth. At least without a little subtle persuasion. Until it’s too late...