Indeed three.js is more like the future but until the webviews in all mobile devices run WebGL fast enough, Unity helps most on the mobile side and one build so

Indeed three.js is more like the future but until the webviews in all mobile devices run WebGL fast enough, Unity helps most on the mobile side and one build so it is used. When WebGL runs fast across the board, many games can just use that for all platforms. I personally love three.js but use Unity, Lime/Haxe/OpenFL and Cocos because of mobile first.