Okay but how do you compute an image? How would your browser -- or any other client software -- know what's the hero image of a blog that you never visited before, for example?
I feel like I am missing something important in your comment.
The article describes computational method of rendering frosted glass effect. You can achieve the same thing by rendering the effect once (then upload to a sever) and have client download the rendered image. Or you can compute the frosted glass effect. What's better? That's the argument.
It's like people forgot what graceful degradation and progressive enhancement is.
Ah, sorry, I didn't make it as far in the article.
IMO it really depends on the numbers. I'd be OK if my client downloads 50KB extra data for the already-rendered image but I'll also agree that from 100KB and above it is kind of wasteful and should be computed.
With the modern computing devices we all have -- including 3rd world countries, where a cheap Android phone can still do a lot -- I'd say we should default to computation.