The toggles to filter user activity in their pages to just what they posted entirely themselves, keeping notifications to just the dashboard instead of constantly at the edge of your eyesight, putting computer on sleeping mode then when you come back the "(№) new posts! click here to view them." bar not showing up after a refresh...
All fantastic design choices/happy accidents that don't keep users as nailed for long stretches of time to this site. All features I'll dearly miss and be extremely unhappy no other social media platform will ever implement for being anathema to their hunger for endless growth. More than anything, I'm glad to have been on a website that cared enough for its users to give them these guardrails.