Can you please explain how Apple was the last to hold out for those of us who are ignorant on WebGL.

Mozilla were the first to implement (Vladimir Vukićević’s work) with Opera around about the same time. Chrome jumped on board a few years later, and IE as of version 11. Apple was the holdout for basically unknown reasons (they’ve had a working version preffed off for ~5 years now) but the basic assumption is that graphics card drivers needed to be hardened to provide a secure execution environment for shaders. It’s one thing to buy a game and give it root, quite another to load a webpage that could start a WebGL process in the background and load executable code onto the graphics card.

Security is definitely the likely candidate (it was for Microsoft as well): even on Yosemite, where they enabled WebGL by default, there's a per-site permissions interface similar to things like location services access.

They only recently added support on iOS devices: http://caniuse.com/#feat=webgl

It was disabled by default on desktop before Yosemite too.

It is still pretty limited on mobile devices.

On my S3 I have to enable it on Chrome and most people are using the native Android browsers.

On my Windows Phone, my 3D samples turn into a wireframe models.

It looks great on my Nokia 822 Windows Phone running 8.1.

IE dies on a Nokia 630, on a S3 running Android 4.3 got a blank screen with the native browser and Chrome, just got lucky with a S4 running Android 4.4 with Chrome after some thinking time.