I agree and prefer black blacks. It's very common in design books to say that's an absolute no-no, however. So graphics people must think it looks better somehow.
Funny how that changes all of a sudden, with the whole history of printing being an effort to get as close as possible to perfectly black ink on perfectly white paper.
Even for body text? I've seen advice that titles should be gray, but that's to make it subjectively match black body text, because bigger text looks darker.
So wrong. #191919 is very high contrast. Many/most sites use #333 for the text most of us perceive as "black". You can also check contrast ratios on a number of sites and you will see that #191919 & #fff make a pair that pass all guidelines at all text sizes.
In the case of white being darker than #ffffff, you can at least argue that most users have their monitors configured too bright (it's too bright by default because that looks better for a short term comparison, and most people don't change the defaults), so darker whites are compensating for that. There's no good reason to make black text gray.