I think we're well on the way ...
Was recently pretty shocked, searched for "gas heating repair" and got back at the top some sites with my suburb name in the title. Naturally I thought, wow, if there is a local place I should go there. Clicking into it, it has everything about my suburb - a picture of the local park, and whole paragraphs of random text containing bits and pieces about the local area interspersed with odd sentences about gas heating ("Cold mornings in XXX can be confronting without effective heating" etc). The text kind of makes sense but also reads like it was generated by GPT3.
Of course, then I realise, this is all SEO. They have generated a page like this for every suburb in my city. There are tens of thousands of such pages they are hosting. The most shocking thing is this is a small time gas repair dealer. They clearly don't know how to do this, they've gone with a low budget to an SEO firm who has effectively generated a giant plume of toxic content into the web atmosphere, all to create a marginal benefit for this one small company.
If a small time low budget unsophisticated company can do this, then I have to assume it's happening everywhere. On a mass scale we have giant smoke stacks all over the internet spewing toxic plumes into the atmosphere. And the humans are gasping trying to find the small bits of remaining breathable air.