I get a similar behaviour on my Android phone. As I mentioned in the article, that example doesn't work on most phone LCD screens. Try it on a real desktop monitor!
You keep saying this, but many people don't have a real desktop monitor. Laptop sales exceed desktop sales and both are dwarfed even by tablets alone.
So whether it's technically the correct approach is irrelevant for a large proportion of potential end-users, for whom it will look broken.
Anyway, I think you have bigger problems than gamma with those devices anyway (glare, reflections etc.), so that's probably the least of your concerns.