No doubt *you* are able to make good documents with or without the aid of AI.
With outright AI 'authorship' you immediately run into potential
copyright issues-- which I think is the origin of the "generated by"
prohibition, otherwise I think disclosure would be sufficient.
Taking a step back: is Bitcoin's welfare maximized by permitting LLM glurge submissions in standards documents? In some cases it's benign, I readily agree, in others its harmful. But the number of good submissions that could be made would hardly be increased by LLMs (being limited by expert proposers with good ideas) but the number of potential poor submissions is increased astronomically. So I think it's pretty clearly a net harm to have text authored that way.
I've never had an impression that drafting was at all a limiting step in writing BIPs, though even to the extent that it has been at times it's possible to use LLMs in a review capacity to make authorship much easier ("What's missing / unclear?") without resorting to using it to author.
There is a particularly clear pattern at least with current LLM tools that users who lack the skills to have authored the work without an LLM are generally unable to recognize when the LLM is full of crap (and even sometimes when they should know better), so unfortunately they're only benign to use in the hands of those whose need is the least.
And as a reviewer outside of Bitcoin I've found LLM powered proposers to be absolutely the worst to deal with. Because they're not submitting their own words and ideas, they're unable to change their thinking in response or explain sufficiently to change yours--- the interactions often degrade to them just copy and pasting their chatbot back to you. Because it's cheap to generate more text they also tend to flood you out with documents several times longer than any human author would have bothered with.
I think LLMs have generally created something of an existential threat to most open collaborations: Now its so easy to get flooded out by subtly worthless material. Many projects, including, Bitcoin have long struggled with review capacity being limited and a far amount of time waste by thoughtless (or even crazy!) submissions, but now it's automated and even the most well meaning person may now make submissions that are as bad as the most deviously constructed malicious submissions could have been in the past, not even know they are doing it, and can make a dozen proposals before lunch without even breaking a sweat.