I can think of a few reasons right off the bat, these are based on some of my experiences so not everyone might feel the same or agree. This is mainly towards radical feminism (and DEFINITELY liberal feminism). Not sure if my criticisms are strong enough for the cancer point, I would hope they are lol but I am open to opinions

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1. For some women, it seems to promote reduced accountability for choices or behavior.
2. Fails to address the fact that rich & attractive women are greatly overrepresented as spokes people of the movement (not trying to insult them for being that though, It's not their choice), which leads to bias and unfair ideas/perspectives, and also ideas irrelevant to many. Also can encourage exclusionary acts/behavior despite claiming to be "inclusive", but most try to deny this.
3. Some of those promoting radical/liberal feminism encourage others to virtue signal instead of take real action about real issues.
4. Some radical/liberal feminists seem to like to glorify cheating against men which I find vile and stupid.
5. A lot of women sucked into radical/liberal feminism become bitter and mean, and resort to attacking and trying to discredit other women instead of actually lifting them up and promoting true equality, hence they become extremely hypocritical and accidentally promote patriarchal values instead.
6. It encourages some women to pull the victim card far too often. An example of this is an extremely incompetent, mean, and bitter coworker I had who was a minority and a women who was 100% a radical/liberal feminist (confirmed by her FB profile and her words at work). She complains/complained about how unfair the world is and how mean white people and men are, but she herself took advantage of men and work for her own gain and even flirted with them when she apparently had a BF to gain earnings and get out of her shit poor performance. She took ZERO responsibility for her actions and put ZERO effort to become a better person, she was a vile disgusting no-talent mean bitch, despite blasting other groups as horrible hypocritically. Sadly I suspect she was a poor example of a diversity hire, and she made people from her background look terrible which was a shame. Ironically despite all her claims of being "oppressed" in a sense she was less oppressed than me because she was more popular and rich than I was and didn't have to work anywhere near as hard as I did.
7. It encourages group-think.
8. It encourages concern about petty issues that just don't really matter and don't really help empower women.
9. Some people use it for their own gain/to make money more than empower women.
10. Many radical/liberal feminists fail to even promote or follow the values which they speak of.
I wanted to mention that I'm a woman myself. I also used to support this neo feminist stuff until I saw the dark side and realized the insane hypocrisy of it.
I also would like to say despite my comments, I don't believe all feminists are bad people necessarily. I also do support general women's empowerment and equality.
I am also sorry if I wrote anything that somehow offended someone or struck the wrong chord.