Classical liberalism (just to give a concrete political term for those old school liberals) is admirable. I broadly agree with its values and I support all those points you mentioned. The progressive and conservative variants we often see in US politics are blatantly hypocritical and broken.

Unfortunately, liberalism’s core issue is that it’s an ideology based on an abstract concept rather than our physical conditions - it starts with the abstract, fair idea of freedom and attempts to apply it onto material reality. For example, the liberal approach to free speech, which theoretically creates a marketplace of ideas where the best prevail, just turns into a propaganda echo chamber when huge media organisation are owned by business tycoons with political agendas, and when social media companies are financially punished by their advertisers for allowing controversial expression. The utopian marketplace of ideas never really manifests at scale when that marketplace is collectively dominated by the like-minded owning class.

Without adding restrictions (a contradiction of liberty), the huge wealth of some people turns their freedoms into their political power. If the rich owning class can control the economy through a monopoly or similar, they have the freedom to control what news you can find, what products you can buy (if you can’t DIY it, like a computer) and their quality and how safe they are, what jobs they will give you, and so much more.

There are also plenty of other contradictions which we see play out, such as:

• How can we balance freedom of religion with giving people rights that a religion rejects? (e.g. abortion, homosexuality)
• How can we balance someone’s individual rights with someone else’s right to private property? (e.g. trespassing, restriction of the commons)
• How can we balance someone’s individual rights with community safety needs and expectations? (e.g. weapon rights, industrial and environmental restrictions, speech laws)
• Should liberalism be allowed to defend itself against a democratically-approved transition to dictatorship, or does this contradict political freedom?

In these situations, we have to resolve them somehow, so we end up with liberalism variants like conservative liberalism and progressive liberalism, straying further from the pure old-school liberalism they necessarily contradict. Even without corruption, liberalism decays, distancing itself from its ideals, and ultimately turns into a playground for the powerful who have far far far far far more ability to realize liberty than almost everyone else.