The AdWords team could have chosen any of a fairly large number of technologies to develop their new front end, but they chose the Dart version of Angular 2 to

The AdWords team could have chosen any of a fairly large number of technologies to develop their new front end, but they chose the Dart version of Angular 2 to do so. CircleCI chose to use ClojureScript and Om instead of using React directly. NoRedInk chose to use Elm instead of writing JavaScript directly. Others have chosen ScalaJS. It's not popular in the startup world, but plenty of companies chose (and continue to choose) to use GWT to build their in-browser user interfaces. I worked at one of them back in 2010. I had huge doubts about the Java-to-JS compilation process. I'd mostly only seen ugly GWT apps cobboled together from the UGLY base components GWT shipped with. As it turned out, we were able to created our own good looking components quite easily. So long before Angular or React existed, we were able to create a nice an easy to understand component based web app, with business logic split out into services and wired together with dependency injection. It ended up being a sane choice that enabled us to continue developing safely and sanely as the app became larger, and it performed very well on both desktop and mobile browsers. GWT wouldn't be my first choice (or second, or third) in 2016, but it ended up being a pretty good one in 2010. I'm not saying that choosing a compile-to-JS language that has very different semantics than JS is necessarily sane and practical. But I think that plenty of real world successes demonstrate that this choice can be simultaneously sane, practical, and successful.