You can make that argument about other services the government provides. It's like saying "Security is a commodity. People who can't afford security guards and private investigators have no right to demand protection from criminals or investigations into their house being burglarized. A poor person's necessity does not change the fact that policing is a service and a good provided by a third party."

We are aware that the current healthcare system treats it as a commodity for those who can afford it. The argument being made is that this is a problem and that we would do better to treat it a public service provided for those who need it.