Medicare is for the elderly and disabled, what he's saying is that he doesn't even understand the Medicare system, and if everyone had both Medicare and or Medicaid they would have to be either 65 or older, disabled, or poor, or both. This social safety net is reserved for the most volrunable of society. The people living off 12 to 15k a year at best. And even then the rules that people have to follow when they receive state funded Medicaid is next to impossible sometimes, and if a poor soul who relies on Medicaid dies, the state can try to recover all the medical expenses from what gets sold off from their life..... Pretty messed up..
And yes offices for health services especially dental offices will refuse these plans because the clientele is rather on the poor side.