The basics of liberalism as we see it today - rule of law and representative democracy, are young. How many presently-unthinkable violations of liberalism were committed by a Western nation within the lifespan of someone who is 90 today, with full public support? Outright genocide, systematic persecution and disenfranchisement of whole races and genders, violent militarised colonialism, you name it.
Building a just state and society is a slow, delicate, multi-generational project of structural and cultural modification, and we are just at the beginning. We're just now getting to a place where we're moving past barbaric mass violence and mass racist persecution.
It's like people look around, notice that we're not in fact in some enlightened Star Trek utopia, declare the whole edifice rotten, and decide that the best response is to gleefully burn it all down.