[hakfoo]

I want to say it's that they learned their lessons from history.

IE, and to a lesser-extent, pre-Chromium Edge became instruments of active developer hostility. I know people who still have to support an embedded IE7 component.

To truly fix Edge, they'd have to keep a constant and large development effort to match Chrome/Safari/Firefox point for point. For a product that even their strongest advocates will admit is basically a "pack in" product of relatively minor market share. It's like telling them "You've got to retool MS Paint to compete with Photoshop."

Of course they'll pick the easy road, slapping some paint and customizations on Blink. Although they could have at least bought into Gecko.