Plus all the other things that software engineers generally have not learned to a professional level even if they picked up the basics on the job by osmosis, because figuring out the customer's needs (and what they'll pay you for which may be different) is the job of a business analyst, a PM, or a UX researcher, and those are different skills and two of them may come with a Business Informatics degree rather than a CompSci one.
LLMs can be "eh, better than nothing" at many things, not just code.
Plus, this is software "Engineering" we're talking about, which famously gets scare quotes in comparison to all the other forms of engineering because unlike them we don't have as standard things like professional liability insurance to cover serious professional errors of judgment the way someone who signs off on a bridge that collapses would have.
> How would they know
How would you? The answer is the same.
If you're implying chatbots can ask their "client" what to build, good luck with that—contractors are at least liable for what they produce and have extreme incentives to ensure that their clients are happy. To the extent of refusing to build anything if they don't know what they want....