When I started making website professionally, a long long time ago. The time of building a website on Internet Explorer 6 and having to support 5 and 5.5. Yes, that long ago. That was also the time Firefox came up and Chrome didn't even exist yet.
Anyway, since that day. Internet Explorer was this thing. We would build our website in either Chrome, Firefox or Safari and later check Internet Explorer and make it work. Most of the time it wasn't that bad, because you learn what what browsers do and don't support and simple fixes could be applied.
But, an era has passed.. Internet Explorer isn't supported anymore and everybody is advised to used the next sucky browser: Edge. They started well, because Internet Explorer had quite a bad name, so a new product would be a good idea. It was gonna be a browser which was gonna support more All other browsers actually do.