LLMs caused this decline. Stop denying that. You don't have to defend LLMs from any perceived blame. This is not a bad thing.

The steep decline in the early months of 2023 actually started with the release of ChatGPT, which is 2022-11-30, and its gradually widening availability to (and awareness of) the public from that date. The plot clearly shows that cliff.

The gentle decline since 2016 does not invalidate this. Were it not for LLMs, the site's post rate would now probably be at around 5000 posts/day, not 300.

LLMs are to "blame" for eating all the trivial questions that would have gotten some nearly copy-pasted answer by some eager reputation points collector, or closed as a duplicate, which nets nobody any rep.

Stack Overflow is not a site for socializing. Do not mistake it for reddit. The "karma" does not mean "I hate you", it means "you haven't put the absolute minimum conceivable amount of effort into your question". This includes at least googling the question before you ask. If you haven't done that, you can't expect to impose on the free time of others.

SO has a learning curve. The site expects more from you than just to show up and start yapping. That is its nature. It is "different" because it must be. All other places don't have this expectation of quality. That is its value proposition.