> People who cannot see the differences or who only see them after taking a close look should realize something: there are many people for whom the differences are going to be immediately obvious.

That's one possible conclusion. Another is that some people are overstating how obvious it is. I don't mean this as an insult - there's plenty of cases where people's stated perceptions and preferences disappear when tested under strict conditions (hello Audiophiles).

So - it's not immediately obvious whether claims such as yours are trustworthy.

(for the record I can see the difference but it's fairly subtle on my screen)

It's definitely an objective phenomenon but there's two factors at play: first is the monitor quality. I have two monitors of the same model number but made in different years with obviously different panels (color reproduction is all over the place between them), and the banding is obvious in one monitor but not the other. I can drag the window between screens and it disappears. On my iPhone, it's very obvious.

Second is how much each person's brain interpolates. I got used to those visual artifacts on the web in the early 90s so my brain started doing its own interpolation. It took reading the entire article and flipping tabs back and forth to compare images before I noticed the difference. Now I can't unsee it in other images that I recently converted to webp for a project.