how so?

I recently ran into this. I was putting an SVG into an <img> tag and sized it with CSS. In every other browser, it worked as expected. The SVG filled the space and stretched to the set dimensions. In EDGE, the SVG appeared tiny at the top-left of the space the <img> took up. I could not figure out a way around it. Had to convert it to a PNG. It seems that it handles SVGs as background images just fine.

I use SVGs all the time in Edge, styled appropriately. Edge however considers (as the spec says) that the bounds of the image are at the bounds of the "page" (as Inkscape sees it, in my experience)

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.