Radical feminism has been fairly mainstream for decades.

The academic definition of radical feminism is basically "feminists who unironically believe in the patriarchy". There's sightly more to it than that, but 9 times out of 10 that's what it comes down to.

Early radical feminists didn't use the term patriarchy. They just believed that men oppressed women similarly to how white people oppress black people. It's a product of the civil rights era -- privileged white women trying to appropriate the suffering and oppression of black people on to themselves.

The irony is you could rewrite that article you posted from the perspective of a blank person talking about a radical feminist.