I'm not a web developer, but with my end user and IT Support hats on, Edge always seemed like a nice rendering engine wrapped inside a half baked User Interface.
The incomplete status it launched in on the first few versions of Windows 10 (Probably up to around Anniversary Update) burnt users badly, and it got the reputation of not being very good that it just couldn't shake - about 30% of issues we saw with the RTM Windows 10 release were fixed by setting the default browser back to Internet Explorer or Chrome.
I think this may be the little talked about downside of releasing early and often to the general populace.
Biting the hand that feeds IT
