The most positive metaphor I have heard about why LLM coding assistance is so great is that it's like having a hard-working junior dev that does whatever you want and doesn't waste time reading HN. You still have to check the work, there will be some bad decisions in there, the code maybe isn't that great, but you can tell it to generate tests so you know it is functional.
OK, let's say I accept that 100% (I personally haven't seen evidence that LLM assistance is really even up to that level, but for the sake of argument). My experience as a senior dev is that adding juniors to a team slows down progress and makes the outcome worse. You only do it because that's how you train and mentor juniors to be able to work independently. You are investing in the team every time you review a junior's code, give them advice, answer their questions about what is going on.
With an LLM coding assistant, all the instruction and review you give it is just wasted effort. It makes you slower overall and you spend a lot of time explaining code and managing/directing something that not only doesn't care but doesn't even have the ability to remember what you said for the next project. And the code you get out, in my experience at least, is pretty crap.
I get that it's a different and, to some, interesting way of programming-by-specification, but as far as I can tell the hype about how much faster and better you can code with an AI sidekick is just that -- hype. Maybe that will be wrong next year, maybe it's wrong now with state-of-the-art tools, but I still can't help thinking that the fundamental problem, that all the effort you spend on "mentoring" an LLM is just flushed down the toilet, means that your long term team health will suffer.'