GWT had its purpose. You need to remember that it was released before jquery was a thing. And also to realize it was the first (was it?) framework to push the large single page apps that worked in all browsers. It was created so Google could make the AdWords and Adsense UIs.
Today's AdWords UI uses AngularDart. So they've moved away from GWT. But 11 years ago the JavaScript landscape was very different.
[I work for Google, but I was doing GWT dev for 4 years before joining]
Today's AdWords UI uses AngularDart. So they've moved away from GWT. But 11 years ago the JavaScript landscape was very different.
[I work for Google, but I was doing GWT dev for 4 years before joining]