First you must fix the asymmetry caused by how employers have a much better data for "what the market will bear."

That's the real reason why employers "should" be expected to name the first figure. It makes the relationship less exploitative.

Ideally, neither party would offer meaningless pre-interview/discovery numbers and both would be willing to accept nearly any number that made sense after agreeing on the likely quality of the applicant-candidate fit. In practice, neither of those things are true and an early number from a candidate is treated like a late-stage number should be. It's much easier to leave the number out than to try to fix that.

And as an employer, I'm certainly not required to give a number. "Market rate" is sufficient to start a conversation with a serious applicant.

I assume market rate seafood is going to be overly priced, I assume market rate salaries are going to be middling and uninspiring. I wonder why I assume the phrase "market rate" is a ticket to frown town?