This is exactly the problem: statistics. In a problem where every case is unique, any use of statistics is an abuse of statistics.
The roots of Western medicine are arguably pre-scientific, and certainly pre-statistical. We knew and could do a lot of things before we knew what a p-value was.
If what "advancing knowledge" means to you is "accumulating p-values so I can publish papers," this kind of experiment can produce no information whatsoever.
If what "advancing knowledge" means to you is "we think we know what's going on and we think we can do it better next time," the answer is very different. Of course this is what most people, indeed most industries, mean by "learning." We don't have to know absolutely that we know - we don't have that luxury. Instead we need to get things done.
Modern scientific medicine is supposed - no, required (with the increasingly narrow exception of surgery) - to learn only in the first way. Guess what? It doesn't seem to be learning much. Or at least, much of any use. Maybe medicine isn't as much like physics as we'd thought.
it is it is for the case of "oh shit, I just killed a million people because we didn't investigate long term effects".
And you're lecturing me about Godwin's law?
For what it's worth, long-term effects of OTC non-cancer drugs aren't investigated for shit. I'm permanently achlorhydric from permanently solving my GERD with daily omeprazole. As recommended by actual doctors. What the hell is the effect of taking omeprazole for a decade? Who the hell knows?
And that is where your theory really fails; because you are trading an unknown collateral now, for an unknown collateral in the future.
Did you ever read Asimov's Foundation? Remember the bits set on Trantor? Your whole mindset is straight out of Trantor, I fear - and it's certainly not exclusive to you.