One of the things that always surprises me about Dart is that Google continued to invest in it for so long without any real returns until fairly recently. Dart came out in 2012 and to my knowledge had basically no usage for several years. Flutter came out in 2017, and then it took a decent amount of time to start picking up steam. Very uncharacteristic of Google to invest in something like Dart for 7+ years before it really started seeing any returns on the investment.