Agree. I was a liberal once. Not just a pro-capitalist with shitty values. But someone who read the theory, did the homework, and accepted (a) the limits of human social possibility and (b) that capitalism was the only option to improve the world. But because I was so invested and so critical, I saw the flaws and the contradictions.
The problem is that liberalism offers zero tools to cope with or resolve those contradictions except for curious philosophical thought experiments. Then someone patiently explained a way of thinking that engages with and resolves those contradictions i.e. historical and dialectical materialism.
Another problem for western 'progressive' liberals is that they live in an echo chamber and have no awareness of it because they are convinced that freedom of expression is a thing capable of existing. It isn't, because the ruling class control intellectual production and distribution.
The thing with online discussion is that you don't have to convince the person you're talking to, or you don't have to convince them there and then. It creates a public record that others will see and come across. Simply by providing a counter narrative, the spell can be broken.
It's like when we try to engage with libs here or elsewhere and they all gang up on you with their ill-considered ideas. They don't make an argument because they think that everyone will agree that any unorthodox ideas will be treated with disdain ab initio. They can't make an argument because that requires logic and evidence, neither of which are on their side.
By providing a counter narrative, we highlight this and show to those who see the cracks in liberalism that there are sensible, reasonable, well-read, and rigorous thinkers who don't accept the liberal bullshit. By engaging with liberals, we create the possibility of escaping the liberal mind trap.