Radical anything is the opponent of progress. It shuts out the exchange of thought and understanding. How can you attempt to change the way people think if you're not even interested in how they think already?
That isn't what 'radical' means in this context.
But it really is. Their main point is how right women are at the expense of men based solely on the horrors that men have put women through. There is no part of radical feminism that lends any credence to the perspective of men. No, it's not literally the same thing as most things described as "radical" but that's mostly because the roots of feminism are really quite reasonable. But the movement you could describe that way has become so ridiculous in its repulsion towards men that it's just ignorant. It is so deeply rooted in the wrongs of men that there is nowhere to go once men have been beat down in the ideal result of the movement. That's because of the absolute dismissal of the male point of view. That gives in namesake an appropriate level of accuracy based on what "radical" is usually meant to describe.