What are you talking about? IRBs have been around for 50 years. So 50 years of history we have been consciously not pursuing certain knowledge because of ethics.

It would really help for you to just say what timescale you're setting as your standard. I'm getting real, "My cutoff is actually 51 years"-energy.

Just accept that we have, as a society, decided not to pursue some knowledge because of the ethics. It's pretty simple.