The issue is that it's creating a market for such content, and the production of the content inherently entails harm (sure we can split hairs over whether a 17

The issue is that it's creating a market for such content, and the production of the content inherently entails harm (sure we can split hairs over whether a 17 or 16 year old is mature enough to produce porn, but I think we all agree that there exists a threshold where that is no longer the case). While I do think concern about over zealous enforcement is warranted, and opens up potential for abuse (e.g. embedding illegal content in other files to troll or extort people), I don't object to the principle behind banning it even if it is "certain configurations of numbers".