The same thing happens with displays. Designers and devs are using things like high-end Dell Ultrasharps, LG UltraFines, the integrated screens in MacBook Pros, iMac 27" displays/Studio Displays, Pro Display XDRs, etc but in reality a huge number of the screens in use are things like those terrible 1366x766 TN panels that dominated budget 10"-17" laptops for over a decade. I'm fairly confident the low-contrast flat design trend that's been going for a while now wouldn't have been a thing if it were a requirement for UIs to be usable and reasonably good looking on a crappy $250 Walmart special Dell Inspiron from 2012.
The wonderful thing about webpage design is your user don't give a f**k about color correction. Monitors nowadays are almost shipped with a default configuration of high saturation, high contrast, high color temperature. To the point that I think standard srgb 'paper white' is pointless for webpages. Because virtually nobody except designer themselves will enable it on their monitor.
Maybe some group should get consensus about modern monitor 'paper white' so at least everybody has a daily monitor in same setting no matter how good/bad his monitor is.
