At the very least for programming the decline of improvement compared to difficulty of task and skill of programmer quickly got into "AI technically helps but time spent fudging with prompts is more than time saved".

However if your task is to write some SEO slop about your products for your company's webpage, or to make a bunch of business emails to customers, I can absolutely believe AI can double productivity there, there is nothing of value produced that requires skill, it's just a few bits of info filled with fluff around them