Yeah and that's because nobody (from the browser vendors to the game engine providers) has bothered to create decent tooling for real-time 3D and game developer

Yeah and that's because nobody (from the browser vendors to the game engine providers) has bothered to create decent tooling for real-time 3D and game developers to be able to effectively deploy HTML5, with a specific focus on reducing build sizes via a combo of compression and a lazy loading asset fetching system. This is what our startup has been focused on for Unreal Engine 4 to target WebGL. We've achieved scenes that are sub 10MB that load in up in two seconds in the browser on most devices.