There's a great wikipedia page on this very topic [1]. In some countries like Germany fictional porn isn't considered porn, while other countries like Australia or France consider the possession of drawings of naked minors a crime worthy of jail sentences. And then there's the US where having the images on a computer is fine, as long as they aren't sent over the internet and the computer never crosses state lines.

In general it's a topic people are careful about because the legal situation is complex, and in many countries associated with the potential of heavy jail sentences.

1: https://en.wikipedia.org/wiki/Legal_status_of_fictional_porn...