i use tumblr and ao3 quite often, and while they aren't in the same category of website really, one being social media platform while the other is an archive of internet fiction, using tumblr makes me appreciate ao3's lack of algorithm every day.
sometimes i'll zone out while using tumblr, staring at something on my desk or just getting lost in thought, but i had stopped scrolling on like, an nsfw post or whatever so now the hyperactive tumblr algo assumes that that is the only content i want to see so thats what my feed becomes. im very glad ao3 doesnt do this, i can ponder a fic and consider it heavily and when i scroll to look at the next one, it is not at all just recommending similar content to the one i happened to be staring at last.