You have to look at it as an entry barrier that protects them against competitors too. If they are the only ones offering this setup, they can charge very high prices and recover the initial investment relativelly quickly.
> look at it as an entry barrier that protects them against competitors too
What barrier to entry? Their customers don't care that OSX is running under the hood. You can offer an image processing service using any platform today. Sure, on Linux it probably wouldn't be as efficient, but it doesn't have to be. Scaling is a Good Problem to have.
Basically, as you grow, it helps to take a critical look at risk factors and the technical debt which contributes to that risk. The longer you wait to pare down that debt, the more expensive it is, and the more exposed you are to that risk. A little more work up-front saves a lot of work later on.
(I'm the datacenter manager at imgix, and I wrote the article)
I completely agree with your concerns, and I'm constantly evaluating our business for operational risks and inefficiencies. There's a lot of stuff that I can't share in public about this, but what I can say is that the math works out (for now): OS X graphics processing is worth the downsides. It may not always be the case, and we're built in a flexible way where we can make a change when it makes sense to do so.
How different is it? Aren't they dependent on OpenGL and Nvidia/AMD GPUs/Drivers themselves? Wouldn't it make better sense/efficient to invest in becoming platform agnostic and optimize this.
I only say so cause it seems like Imgix could massively benefit from such a move and maybe look into other solutions which you currently can't consider (Custom ARM silicon - PowerVR-based servers, Professional AMD/Nvidia GPUs, etc)
Without going into too much detail about our stack, there's quite a bit more to Core Image than OpenGL+graphics card driver.
Those are important components, and we're not talking about splitting the atom here, but Apple has had a number of smart people working on graphics technologies for a long time now. imgix also has a bunch of smart people working on this, but for a much shorter period of time.
