Sexism is about exploitation to keep selfish individuals in powe. Liberal feminism is trying to regulate that system so it is less exploitative. Radical feminism is getting rid of that system to replace it with one that doesn't exploit females. Both routes have been used in history for other exploited groups.
Often an environmental factor precedes a revolution. They often begin as strikes after famine or disease. It's a sort of all or nothing thing combined with the realisation by those doing the exploiting that if the workers stop working then the powers starve too. Eg. French rev, peasants revolt 14th century
Liberalism is a more gradual process with regulations happening here or there after studies show that it in some way benefits the current system. For example 19th century factory laws or the vote gradually introduced for different groups 19th and 20th century. It was realised that if you give people something then they feel they have something to work for.
I guess it comes down to fog (fear, obligation and guilt) that stops out and out revolution because we have families to feed and don't want to strike etc. Therefore we tend to use the liberal route as it is less physically dangerous and we live fairly comfortably so don't see the need to be more radical.
I'm not judging either route, just analysing it in a amateurish way admittedly. I guess there are levels of radicalism too as there are levels of Liberalism. Radicalism can go too far and start to eat itself if there isn't an ultimate plan and a point where it is agreed that they have reached the final goal eg French terror or other dictatorships after revolutions.
It probably comes down to why people want power...to help the many or the few. Do we want to be equal and free to help humanity in general or do we want to be in control ourselves for our own personal benefit? Or both?
I have always been a feminist but only recently thought about what I can actually do to sort this exploitation out. I tend to see it as a bigger picture of human group dynamics and how it swings from functional to dysfunctional. I know that pisses off some feminists because they believe it dilutes the specific argument about female rights to include children and other exploited groups but I feel it's all part of the same problem.