Earlier quoted context omitted.
I understand; even in the case of "power imbalance" relationships, I'm still asking the question: What is the evidence these are primarily negative relationships for the participants? When you read about these, the authors almost exclusively present it as the person in the dominant position somehow taking advantage of the other. Are you equal, though, in your condemnation of e.g. the flirty student successfully seduc…
Years ago, I had intense debates with my mother about the Monica Lewinsky case. I made essentially the same point you're making here: that focusing on the power imbalance stripped Lewinsky of her agency as an adult woman. My mother's arguments that Bill Clinton had too much relative power (and was too much older) for the relationship to be reasonable didn't really sink in for me at the time. As I've learned more abou…
Clinton morally erred by breaking his vows to his wife, but if we set that aside, he did not do anything wrong by the simple act of having sex with Lewinsky. Let's assume, though, that the power differential argument _is_ valid- Who _could_ he engage in a relationship with, being President? Not politically powerful women, because his power is always going to be greater. Maybe other world leaders only? Only world leaders in the G8? He has no peers.
The student/professor example has a few _practical_ concerns regarding why you might want to avoid that situation and you've laid those out, and I agree. But ethically there would be no cause for objection unless actual grade massaging was occurring. That's not a given. In other words, appearance of impropriety is a practical objection, not an ethical objection. I'll zing any professor for taking advantage, express or implied, of one of her students but I will not automatically assume something shady is happening without evidence.
Anecdotes are not data. If we can show that the majority of these relationships are negative, that's a stronger case, but still not worth blanket-ruling the exceptions out of existence.