I accept there are productivity gains, but it's hard to take "10x" seriously. It's such a tired trope. Is no one humble enough to be a meager 2.5x engineer?
I don't know what to tell you, it's just true. I have done what was previously days of BI/SQL dredging and visualizing in 20 minutes. You can be shocked and skeptical but it doesn't make it not true.
There is no x is because LLM performance is non deterministic. You get slop out at varying degrees of quality and so your job shifts from writing to debugging.