> The writing skills that became worthless for this guy were the ones that weren't worth much to begin with.

Exactly. The market price for anything is determined by both demand and supply. The demand for good writing is relatively unchanged. The supply is also relatively unchanged. In the case prior to ChatGPT that demand and that supply were somewhat low, or as you say - not worth much to begin with.

Oh sure, there's always the Stephen King's and Tom Clancy's of the world, but guess what? They were always the exception anyway and they will continue to be. The same argument can be made for musicians.