Service workers provide way more capabilities than just creating a shortcut. Google’s doc[1] provides a good introduction, but essentially you get things like push notifications and background sync in a cross-compatible way (chrome, Firefox, Edge, and now Safari). I’m particularly excited about the caches and sync APIs, which allows sites to be rendered and be interactive even when you’re offline or have a flaky connection.

1: https://developers.google.com/web/fundamentals/primers/servi...