Exactly. Most people who read or write erotica, on CHYOA, for example, are capable of separating the interest in a theme from a need or want to do it in real life. As you say, does that then make Agatha Christie a murderer? I could write about a serial killer or any number of violent themes and nobody would give a hoot. But when it comes to sex, people automatically assume the author must have some personal experience or deep longing for their subject matter. It's infuriating.
Some books have gone a long way to normalising previously 'dodgy'' themes, Game of Thrones did, to some extent, make incest as a fictional subject matter more acceptable. 50 shades of grey is a god awful book, it's poorly written and far from accurate in its depiction of BDSM, but it has brought BDSM, and erotica in general, into the mainstream arena which is a good thing in my opinion.
