There are sex-themed text adventures (e.g. Drive-In in which you're at a Drive-in movie theatre with a date: https://ifdb.org/viewgame?id=gksf13iptntcx5m6 ) but most of the people writing "amateur literotica" are middle-aged women and the pre-VGA era PC has far fewer of those proportionally.
In terms of more conventional erotic literature (not branching narrative) that takes off more with widespread access to the Internet because it connects writers and audience. Today authors can gently shade over, from giving away fan-fiction on AO3 to producing cheap Amazon e-Books that make you enough to buy a coffee once in a while, to getting paid professionally to churn out stories for an outfit like Harlequin that can afford actual editors (even if you read two Romances a day like my mother, the fact Jim got taller and grew a beard in the course of a single chapter jumps out, not to mention the fact his older brother's name changed, and so she can tell if she's reading a story that a professional gave the once over before it was published). The Internet also caused readers to explore more, instead of buying a box of a dozen Edwardian-era Romantic fiction novels at a time, knowing that's more of something you like, when it's one click away why not find out whether you're into werewolves, or gay relationships, or the Wild West, or whatever? If you hate it you can click away and be reading yet more stories from the early 20th century British Empire in seconds.
