Microsoft says people are inclined keep their tabs open indefinitely with the intention of going back to it later. Think about it -- when you suddenly become too busy to fill out a website's registration page or to read an interesting long-form story you find, you tend to leave the tab open. Sometimes you even forget about it until it gets buried under dozens of other tabs. The snooze button sounds like a much better option than leaving multiple websites open or digging for URLs in your History.
Besides the snooze action, the new build also introduces new Edge extensions, including a smart shopping cart that you can use to set price alerts for products you save. More importantly, if you're running an older Preview build on your PC, expect to get a notification to upgrade once a day. If you still don't update by October 1st, your computer will reboot every three hours. And if you insist on putting it off, your PC won't even be able to boot up by October 15th. You should probably set a snooze reminder to make sure it doesn't get to that point.