They are (or were) academically accessible. Remember the Cornell/Facebook study on emotional contagion? It's not a matter of whether the study could be done. I

They are (or were) academically accessible. Remember the Cornell/Facebook study on emotional contagion? It's not a matter of whether the study could be done. It's a matter of it being incredibly unethical to do it. Signing up for Facebook is not sufficiently informed consent for these sorts of studies.