The title on the page is "The Decameron is dirtier than you remember" and that's true. The reason I think could be that the sexual parts are overshadowed by the "parable of the ring" taken from the Decameron and made famous by Lessing for "Nathan the Wise".
Yes it’s a very dirty book lol. I’ve watched a very old Italian movie Decameron by Pasolini which was pretty fun.