GWT was great for boring tech stories back in the day. It was briefly alluded to in one of the comment I think but, at least to me, GWT's killer feature was porting big legacy battle-tested core GUI SDKs to HTML5 compliant browsers.
e.g., circa 2010, we were porting 50k+ LOC mapping/GIS libraries to the browser and it worked way better than we thought it would. This was a unit tested codebases that were being used for at least 5 years on the desktop. We were also able to get touch gestures working decently on it.
To second another comment, these days WASM would make more sense, but back in the day customers would be taken aback when were able to provide niche mapping features they were used to seeing on the desktop pop up on the browser.
e.g., circa 2010, we were porting 50k+ LOC mapping/GIS libraries to the browser and it worked way better than we thought it would. This was a unit tested codebases that were being used for at least 5 years on the desktop. We were also able to get touch gestures working decently on it.
To second another comment, these days WASM would make more sense, but back in the day customers would be taken aback when were able to provide niche mapping features they were used to seeing on the desktop pop up on the browser.