Good ideas propagate. Nobody from an AGI org has to read a LessWrong post for any good ideas generated here to reach them. Although they definitely do read Alignment Forum posts and often LessWrong posts. Check out the Alignment Forum FAQ to understand its relationship to LW.

LessWrong and AF also provide something that journals do not: public discussion that includes both expert and outside contributions. This is lacking in other academic forums. After spending a long time in cognitive neuroscience, it looked to me like intellectual progress was severaly hampered by people communicating rarely, and in cliques. Labs each had their own viewpoint that was pretty biased and limited, and cross-lab communication was rare, but extremely valuable when it happened. So I think the existence of a common forum is extremely valuable for making rapid progress.

There are specialized filters for LW by tag. If you're not interested in AI, you can turn that topic down as far as you want.

Just wanted to point out that AI Safety ("Friendliness" at the time) was the original impetus for LW. Only, they (esp. EY, early on) kept noticing other topics that were prerequisites for even having a useful conversation about AI, and topics that were prerequisites for those, etc., and that's how the Sequences came to be. So in that sense, "LW is more and more full of detailed posts about AI that newcomers can't follow easily" is a sign that everything is going as intended, and yes, it really is important to read a lot of the prerequisite background material if you want to participate in that part of the discussion. 

On the other hand, if you want a broader participation in the parts of the community that are about individual and collective rationality, that's still here too! You can read the Sequence Highlights, or the collections of resources listed by CFAR, or everything else in the Library. And if there's something you want to ask or discuss, make a post about it, and you'll most likely get some good engagement, or at least people directing you to other places to investigate or discuss it. There are also lots of other forums and blogs and substacks with current or historical ties to LW that are more specialized, now that the community is big enough to support that. The diaspora/fragmentation will continue for many of the same reasons we no longer have Natural Philosophers.

LessWrong is becoming more and more specialised, thus scaring off any newcomers who aren't interested in AI. 

Yup, sorry.

Do any of the posts on LessWrong make any difference in the general psychosphere of AI alignment?

Sometimes. E.g. the Waluigi effect post was in March, and I've seen that mentioned by random LLM users. CNN had Conor Leahy on as an AI expert about the same time, and news coverage about Bing chat sometimes glossed Evan Hubinger's post about it.

Does Sam Altman or anyone at OpenAI engage with LessWrongers?

Yeah. And I don't just mean on Twitter, I mean it's kinda hard not to talk to e.g. Jan Leike when he works there.

What are some basic beginner resources someone can use to understand the flood of complex AI posts currently on the front page?

Yeah, this is pretty tricky, because fields accumulate things you have to know to be current in them. For "what's going on with AI in general" there are certainly good posts on diverse topics here, but nothing as systematic and in-depth as a textbook. I'd say just look for generically good resources to learn about AI, learning theory, neural networks. Some people have reading lists (e.g. MIRI, Vanessa Kosoy, John Wentworth), many of which are quite long and specialized - obviously how deep down the rabbit hole you go depends on what you want to learn. For alignment topics various people have made syllabi (This one, I think primarily based on Richard Ngo's, is convenient to recommend despite occasional disagreements)

(2) What are some basic beginner resources someone can use to understand the flood of complex AI posts currently on the front page? (Maybe I'm being ignorant, but I haven't found a sequence dedicated to AI...yet.)

You can check out the recommended sequences at the top of the AI Alignment Forum (which is a subset of LessWrong).

To add onto other people's answers:

People have disagreements over what the key ideas about AI/alignment even are.

People with different basic-intuitions notoriously remain unconvinced by each other's arguments, analogies, and even (the significance of) experiments. This has not been solved yet.

Alignment researchers usually spend most time on their preferred vein of research, rather than trying to convince others.

To (try to) fix this, the community's added concepts like "inferential distance" and "cruxes" to our vocabulary. These should be be discussed and used explicitly.

One researcher has some shortform notes (here and here) on how hard it is to communicate about AI alignment. I myself wrote some longer, more emotionally-charged notes on why we'd expect this.

But there's hope yet! This chart format makes it easier to communicate beliefs on key AI questions. And better ideas can always be lurking around the corner...

The impact of the LessWrong community as a whole on the field of AI and especially on the field of AI safety seems to be fairly strong, even if difficult to estimate in a precise fashion.

For example, a lot of papers related to interpretability of AI models are publicized and discussed here, so I would expect that interpretability researchers do often read those discussions.

One of the most prominent examples of LessWrong impact is Simulator Theory which has been initially published on LessWrong (Simulators). Simulator Theory is a great deconfusion framework in regard to what LLMs are and are not, helping people to avoid mistakingly interpreting properties of particular inference runs as properties of LLMs themselves, and has recently been featured in Nature as a part of joint publication, M.Shanahan and the authors of Simulator Theory, "Role play with large language models", Nov 8, 2023, open access.

But I also think that people ending up working on AI existential safety in major AI labs are often influenced by the AI safety discourse on LessWrong in their career choice and initial orientation, although I don't know if it's possible to track that well.