To be fair Edge is a pretty solid browser these days, I don't think you can put them on the same league. I've been using it for some time now and other than a slightly different font rendering engine I have yet to find a fault on it; everything works like you would expect in a modern browser. Development wise, we test for Edge ocasionally and so far we haven't come across Edge-specific quirks like the good ol' days of IE.
(Sorry I couldn't help myself)
I do The Bad Thing™ with inline styling on occasion, but I've had no problems:
<img style="width:100%;height:auto;" alt="header" src="https://zaibatsutel.net/zaibatsu-wide.svg">
Works 100% fine in IE using a layout kit like Marx or Twitter Bootstrap every time.
Edge is simply expansive to test for, because at the places where i worked the only windows laptops (that are locked down like Azkaban for obvious reasons) around were those of the sales people. Majority of the developers on linux, where the designers are on macs.
Unless it is actively formalized, Edge ends up not getting a lot of testing with anything we make.