Liberalism is associated with those things because it allowed them to happen to avoid a negative effect to property rights (revolution, riots) once more radical people pushed for them. Liberalism is reactionary and regressive, but some liberals are easier to convince of specific rights extensions than others. You’ve been lied to a lot if you think liberals did these things
Philosophy absolutely has the ability to examine and propose better definitions when definitions (like the ones you linked) do not capture the phenomenon. Losurdo read more books than you’ve seen by liberals in order to write his “Liberalism” book. He understood the phenomenon deeper and further than its dictionary use.
How do you capture such a thing in your world view? Because he found flaws in definitions and worked deeper, he just did nothing because it wasnt the Oxford definition?