> I remember the days people compared their colorimeters and profiled their own monitors.

That would be calibration and it's still necessary if you want color accuracy. That's about ensuring that what your monitor thinks it's displaying and what it's actually physically emitting are the same. The main thing that's changed here is that factory calibration has become a lot more common and is often more than good enough for anything short of serious professional work. Even for things that aren't professional displays. Like most flagship or even midrange smartphones are factory calibrated with dE values that would make reference monitors from 20 years ago blush. Right up until the OEM shoves a shitty color curve on it intentionally to make it "pop" or be more "vibrant" (Samsung calls this "Vivid", Pixel calls it "Adaptive", etc.. - but they at least usually have a "natural" option that gets you back to the properly calibrated display)