The idea that there is a 'mainsteam feminism' is in itself a useful idea to denigrate women you want people not to listen to.
There is no 'mainstream' feminism.
Firstly there are Feminists/ women taking feminist action all over the world. Each area has its own specific culture problems etc and will focus on them. The pushback will take different forms and with different justifications.
So the first assumption is that when anyone data Feminists they mean.. UK? UK and USA? Something like that? Why is it not stated.
Then say it is UK. There is no 'mainstream' feminism. The women who are getting most flack at the moment are second wave types. But large numbers of women have a feminism that says sex work is work etc. Polar opposite. Then there are women from different political stances that nevertheless care about women because they are women themselves. There is also the feminism that says it should be for everyone. There are strands for women with different experiences and characteristics. And so on.
What even is mainstream feminism? I have no idea.
It's handy to say there is one though so that you can ascribe whatever actions to it, and then say how awful they are.
The whole thing is dishonest.
And a lot of people have always disliked/ been suspicious of women who speak out about women's issues. So are more than happy to hear why feminists are awful.
Yes the different viewpoints and failings etc need to be raised and discussed etc. By the women who see the shortfalls.
This is not that. This is creating an idea of something that doesn't exist in order to discredit it.