Form over function has always been a danger; and failure to test your output on a reasonable simulation of what people will actually view it on has always been a mistake; but the contrast is particularly glaring when the gulf between the sort of screens that 'content creators' tend to use and the average quality of screens site visitors are using is so enormous. It has always been there; but it has not always been so wide.
It's not the screen quality where the gap is - it is the eye quality. Designers tend to be young, between 20 and 30, and design for their peers. They have no idea that eyesight deteriorates that fast with age, they just can't image.
Add to that the principle that we tend to find things prettier when their outline is less defined (which happens when you reduce the contrast) and you have recipe for disaster. Designer lowers contrast up till the point where he can still read it, but barely. Everyone with worse eyesight, which is everyone 10 or more years older, can't read the text anymore.