>>14508111
The idea is: I am a woman. I have the option of getting a septum ring. Some men will be turned off by my septum ring and some others won't. I know, intuitively, that I am not interested in pursuing the men in the first group romantically at all and that it won't impact my prospects with the second one as much. Then, to avoid being approached by men who I don't want to fuck, I get the septum ring.
This is kind of an overly machiavellic overview of it though because most people don't go through these steps consciously; they get a septum ring because they like how it looks, and they probably like how it looks because they belong to a "scene", subculture or just a friend group where it wouldn't be socially damaging to get a septum ring. Everything else is just downstream effects, probably desirable ones from the point of view of whoever's getting one.
Also this is particularly done by actual lesbians who wouldn't care about "good men" at all. Minimizing your sexual appeal towards straight men is kind of the point.