The struggle in establishing the next platform on which the future of the internet will be founded has been going on for a while. Flash and HTML 5 have been duking it out and while the latter has won when it comes to mobiles, both are still trying to assert their dominance when it comes to computers.
Since the game is accessed via the browser, it can be played on the computer as well as your smartphone and tablet. While popular game apps are only available to you on a single device (unless you employ some creative use of emulators), BrowserQuest gets a leg up when compared to its competitors.
With work ongoing for 3D environments along with support for controllers and peripherals, browsers may very soon become an extremely viable platform for game development. And HTML 5 may be becoming the de-facto language of choice moving forward to the future.