Wait how is this even controversial. We have decades, perhaps centuries, of precedent in liberal democracy of writing under pseudonyms. Since nearly your entire presence online is via your writing, I don’t see how it could possibly be ethically wrong to write online under a pseudonym. If having a fake image in addition to your name bothers you then just use a blank avatar or something.

The whole point of pseudonyms has been that a) your work should stand for itself and not be impacted by your identity and b) to protect individuals.

Can someone use pseudonyms to perform unethical or fraudulent activity, of course. But the pseudonym itself is not unethical.