"And I do think it is insane to say "I've stopped being a feminist because somebody was a bit mean to me on an internet forum""
Posters have said a little more than that.
I think there are a few issues here.
1 - When talking about feminism on MN and why they do not identify as feminist on MN, it is inevitable that it is going to bring up how many people get told (on MN) that they aren't feminists, or that they are anti-feminist.
2 - A question like this on MN is also going to bring up why people actively avoid the feminism section.
3 - If people have only really engaged with debate on feminism on MN then it's understandable that the feminism section on here will colour their views.
4 - Then there is the confusion over what "equalist" means. And why some people prefer to identify with that rather than with feminism. And also why some people see "equalist" as denying the need for women's right. (As sunshineandbooks explained earlier in the thread)