> Intelligent, educated, and capable adults should be held accountable for their own decisions when they turn out to be poor decisions.
Rarely I'll state something so strongly - this is true at face value but in the context you meant it is so fundamentally wrong it borders insanity.
The entire reason we have regulation and reputation-based systems in place (like diplomas from accredited universities, or the bar, etc.) is to allow the individual to delegate decisions to specialists. That is why practicing medicine without appropriate training is a crime (in most/all countries I know of).
Do you also want me to get out of my car and do some quick analysis of the structural integrity of every bridge I'm going to cross? Or are you goin to blame me if the bridge collapses and kills me?
Again, back to the case at hand - the whole purpose of having medical professionals is to follow their advice.
If they are prescribing you poison the solution is obviously to prosecute them through the judicial system, not undoying every trust-based system that makes complex professions in society even remotely possible/functional