You know, I always thought the exact same thing, but then I started actually reading up on it and the concept behind it is really interesting. To put it simply, libertarian socialism is basically a school of thought of socialism that rejects the idea of centralizing all of the power over the societie and the economy with the government's. So instead of having a command economy where the government controls everything and private property is all but abolished, you get something that actually has a chance of success. It's not perfect, obviously, but it does have some interesting ideas and also some badd ideas no different than any other political ideology. Also on the subject of the words contradicting one another, there is actually some interesting history behind the phrase. It's really only in the United States that's libertarianism is actually associated with capitalism and the right wing as a whole. All the way into the 1800s and even the 1900s, libertarianism was actually associated with leftist anti-authoritarian movements. So that includes anarchists some of these socialist movements, and a few others
