The difference is that on OF the direct contact is part of the sales pitch (perhaps the only part that actually provides "value" since there is no shortage of free porn, including OF leaks) whereas on other platforms it is not (and you are not directly purchasing anything at all but watching ads instead). Onlyfans isn't clickbait here because it is genuinely more scummy than doing this in the other places you mentioned.

That said, I don't agree that using AI chatbots to deceive fans is OK anywhere else either. And no, I would definitely not ever do it myself.