Why can't most AI Editor allow you to edit erotic stories?

Could someone clarify this for me? Since it's private unless you post it, others won't see what you write. Many people write stories for themselves and use AI for editing assistance. Even if they do post, others wouldn't know which AI they used unless the writer mentions it. So why limit what the writer can do? I use two AIs for my stories: one outright prevents erotic content, and the other is inconsistent - sometimes allowing erotic stories and sometimes not.

Additionally, both AIS restrict the number of characters or words they can process at once - typically around 1200 to 1500 words. Why is that? Many writers work with more than that; for me, it ranges from 5000 to 15000 words.