Most content on most users’ screens doesn’t use pure black/white for UI. Most users will (assuming they even know or care how to adjust their monitor, which is far from a given!) adjust their monitor to make most content look good, which will not be the same as making pure black/white UI look good.
So, then if designers stopped lowering the contrast of their sites, users would adjust their monitors back to sensible defaults rather than cranking the contrast to make low-contrast web sites look good. Right now we are stuck in a loop where designers assume users have cranked the contrast too high, so they make low-contrast web sites, so user have to crank the contrast too high...
TBF, I think having a small range of blacks in use is a good thing. Use 0.0 and 1.0 for highlighted items. 0.1 and 0.9 for the rest. Great! A little color rather than grayscale? Great!
But, I've seen far too many sites that take it too far and think they are smart by presenting dim-on-grey text. f2 hex is 0.87 and 22 hex is 0.33. That's cutting my screen's range in half! And, that's much better than many lovingly designed sites I've had stomp over with screen-reader mode, on my 800 nits phone screen!
That every website uses different “blacks” and “white” is the problem though, because it means you have to adjust your screen differently for each website. If they’d just use #000 on #FFF like 20 years ago, you’d only adjust your screen once and be fine.
My point is that nobody is adjusting their screen for your website, and using black and white doesn't imply that people would need to adjust their screen for your website.
What are all of you people talking about? People adjust their laptop brightness at will. I adjust mine all the time for comfort when reading. It is two buttons on the keyboard. All cell phones have easy brightness controls a swipe away and everybody knows how to use them.
Monitors have contrast and saturation adjustment, not just brightness. Since we're talking about text-on-background contrast, I'm (and I figure others are) referring to the contrast adjustment that other devices don't have.
LCD screens don't need contrast or saturation adjustment unless you are a design or photo professional. For any screen really, you set the contrast at the proper level if it isn't already there from factory. We adjust brightness because the brightness of our environment changes during the day.
As I read the thread, the discussion is about reading text on a laptop or mobile screen. For that you need nothing else than brightness controls. And 100% black text on 100% white background is a good default and works well for all users.
