While people may be opposed even in theory to more tame things like a little code completion, there's plenty of room to very obviously notice GenAI slop.
If people use LLM to generate text, they tend to make too much text, and it shows in how offputting it is. LLM may be able to generate a modest text without notice, but people will put in a two liner and get pages of garbage back and use that.
And of course famously the GenAI textures are generally offputting. Maybe you can have 'generic metal texture' and no one will notice, but try for specific details and it generally gets caught.
It is possible that human output that is similarly crappy gets mistaken for GenAI output, but oh well, slop is slop either way. It's just that GenAI extends the slop to unbelievable magnitude.