Earlier quoted context omitted.
You're wrong. You can clearly see a difference between 20ms reaction time (as instantaneous as it gets because of what you say, 1/60 = 16.6666...), whereas 150 ms is a fast reaction but it definitely is a noticeable lag. I wish your opinion didn't exist because how can we expect to get rid of the lag everywhere if some people even claim it doesn't matter.
Well, most of this sub 150ms lag everywhere in the interfaces is actually artificially designed, and believe it or not, some people do prefer it like this, so it's being designed like this. I'm personally for making everything as fast as it would be, but for most people it really doesn't matter.
I am aware there could be something like a non-linear alpha animation, and so there could be a period of time where the alpha is so little, and it accelerates so slowly, that I could miss the first 100 ms of it - but then again because I'm experienced in gui programming, I would consider that.
For the most part people are just bad at optimizing gui, especially in HTML.