That initial percentage is a little misleading. It includes everything that caniuse isn't sure about. Really it should be something like 97.5±2.5 but the issue's been stalled for years.

Even the absolute most basic features that have been well supported for 30 years, like the HTML "div" element, cap out at 96%. Change the drop-down from "all users" to "all tracked" and you'll get a more representative answer.