After 14 years Apple is removing Dashboard. macOS Catalina will no longer support it, and Apple recently removed Dashboard support from WebKit (via Mac Otakara).
First introduced with OS X Tiger in 2005, Dashboard gave users various widgets, like a clock/calendar, calculator, weather, and more. It’s been disabled by default since OS X Yosemite, which is why you’re forgiven if you’ve forgotten about Dashboard.
WebKit’s changelog mentions the removal.