This is a feature, not a bug. If you spend a day discussing, say, Newcomb's problem, and it doesn't change the way you think and speak about similar situations in the future -- if you don't find easier, faster ways of describing the situation, which were previously unavailable to you -- then you've probably wasted a day.

I don't agree with this. Maybe it is because I am new, but I spend half of my time here translating everything into a more common language. I find it easier to keep track of different arguments and reasonings once I translate it into the linguistic matrix I have been using to learn about everything else in my life.

Brand new concepts need new words and terms, but Newcomb's problem isn't one of them. The term "one-box" is jargon. "Omega" is jargon. It speeds up discussion on Less Wrong, not the real world. If I translate those terms into short sentences I can begin to have the conversation with anyone and the reusable terms will bump into topics I remember from other conversations I have had with people outside of Less Wrong and I see no harm in typing four words instead of one.

To beat this to death: If I always talk about Omega as "Omega," I think about it as Omega. If I think of Omega has someone who has a perfect guessing rate at what I am going to do, this reminds me of omniscience and that reminds me of how a lot of Christians view their God. Is there any relation between Newcomb's problem and God? Who knows, but it seems an interesting train of thought. If I end up talking to a Christian about Newcomb's problem and they state that Omega seems like God I have a better recourse already in place than simply saying, "No, Omega is Omega; not God."

That being said, I have to register the terms "Omega" and "one-box" because I am engaging in conversations here at LW. But even if I spent all day talking about Newcomb's problem using these new terms, I do not consider the point of the conversation to have the same conversation faster or easier. Neither do I consider the point to be having similar future conversations faster or easier. Faster and easier are luxuries; they are icing on the cake. I want to learn new concepts and I consider this to be very different than learning new jargon.

Backing up a little, "cliquey" holds negative connotations. In-phrases and technical jargon can be useful but I have also seen other communities latch onto their jargon and begin to skim over what would be relevant distinctions. It also forces newcomers to learn from the top down because they see a lot of words they do not understand. They register the jargon in their linguistic matrix and assign it an estimated meaning due to context. Eventually they can learn that some terms apply in certain circumstances, but they will never understand the concept until someone teaches it to them or they head off to the wiki and look it up.

This site is not newcomer friendly and that in and of itself is not a problem. Newcomers are justified in feeling intimidated because it is intimidating but there is a difference between the subject matter being intimidating and the community being intimidating. If the community is the source of a lot of intimidation because it feels cliquey, that is a bad thing. Labeling it a feature does not make it less of a bad thing.

(Side-note) I have also seen communities "name-drop" terms in attempts at status. That seems less of a concern here.