And Chrome is reportedly more of a battery hog on macOS[1][2] and Windows[3]. So there you go: different priorities.
[1] http://www.techrepublic.com/article/browser-wars-is-chrome-o...
[2] http://www.theverge.com/2015/4/10/8381447/chrome-macbook-bat...
[3] https://www.extremetech.com/computing/230583-microsoft-claim...