There's a decade of history in these engines with a lot of man hours put into them, and they were actively competing with each other very loudly for a while. There's little you could tell me I couldn't find some possible narrative justification for if I consider the PR, bureaucracy, talent and design decisions that might stem from those over a decade.
This is the same Google that is still keeping Allo Web and Google Earth a Chrome exclusive, the same one that has paid adware vendors to sneakily install Chrome, etc.
Sure, you can believe that this is jist a coincidence. But that's one unlucky streak of coincidences. In fact, you'd be more likely to win the Powerball ten times in a row than for all this to happen by coincidence.
This gives a good reason why Google Earth is only on Chrome - https://www.reddit.com/r/linux/comments/66ao68/new_version_o...
Disclaimer: I work at Google but not any of the related teams. I was curious myself about these so I Googled and came across the above two articles so these opinions are of my own.
Another consequence of switching has been difficulty in using things like my Apple TV or Chromecast (e.g. casting a video to my TV), or using my Mac's media keys to control Google Play Music.