Yeah but to reach that point you will probably need those "useless AI detectors" (as stated by the comment I was replying to).
That was my point - we're not there yet therefore those tools can be useful.
I agree with you that the "portion of written content online that’s AI generated with no obvious tells" is "small yet growing". That's exactly the thing - it's still too small to "be there yet" :)
E.g. it's perfectly possible that in terms of prevalence "AI slop > AI acceptable > human acceptable" instead "AI slop > human acceptable > AI acceptable" and nothing noted explains why it is one instead of the other.
Like imagine the Rust Evangelic Task Force, but for the next big thing, will probably be shilled by bots.
Low quality content like Youtube and Reddit comments are probably mostly LLM bots who comment on anything to hide the actual spam comments.