I think they they had to kill their own rendering engine to keep Edge alive. Sticking to their own engine would have eventually killed both. Hard to get people

I think they they had to kill their own rendering engine to keep Edge alive. Sticking to their own engine would have eventually killed both. Hard to get people to adopt your browser if webdevs are not testing sites with it. And webdevs don’t care if your market share is marginal. I believe the alternative would have been most of the enterprises deploying Chrome on Windows to access their apps. With this move Microsoft might still retain control of the app level. This is valuable because then they can for example provide integrated windows authentication for the apps.