Yeah if you don't need add ons or advanced features Edge does a very good job, it's lightweight & clean. But recently MS has been turning to integrating open source systems in place of their own proprietary ones more and more, it streamlines resources, reduces cost, and generally results in something more widely supported, less buggy & better performing. If getting EdgeHTML optimised for ARM was going to be an expensive feat that someone had already done better with an open source alternative there wasn't really much reason to go through all the pain.