Seriously, just stop for a second and use your head.
First, that game? Probably using precompiled logic--especially as games in the last decade have gotten objectively harder to mod. The browser must deal with any arbitrary code shoved at it, and handle modifications to its scene graph (the DOM) at any time. These modifications may include creating more script code, pulling in networked resources, or any other damn fool thing.
Second, that game is only going to run on a narrow selection of hardware. It's not going to run on a machine from ten years ago, probably. It's not going to run on a machine ten years from now, probably.
Third, that game is built to use files and formats specifically made for itself. It's not dealing with old goofy image formats. It's not dealing with potentially malformed XML documents. It's not dealing with any number of things, because those have been trimmed away and pre-verified.
Fourth, that game is never going to have to scale from a multiple-socket workstation all the way down to a handheld phone or shell script.
It's really silly to point at a hyperoptimized purpose-built tool and claim it is somehow massively better than a platform for distributing massively-varied media and documents.
EDIT:
Downvote away--but first, write a purpose-built pipeline for deferred rendering, and then a real-time app in Angular, for example. If you haven't done both of these things, you probably don't know what you're raging about.