The wcag color contrast algorithm isn't great (and there is a proposal for a better one), but sufficient color contrast is necessary for a variety of visual conditions. That it's not good enough for some doesn't mean it's not more accessible than not doing it at all though.
A while back, a lot of Big Tech platforms (most notably GitHub) switched their "should we put black or white text on this user-supplied background color" algorithm to use the WCAG contrast formula. Doing so caused a lot of white-on-red badges to flip to black-on-red.
Many users reported this was harder to read, even those without the form of color blindness which makes black and red hard to distinguish. Whether making this change was really "more accessible" than doing nothing is therefore pretty debatable, but it definitely helped them pass their WCAG audits.
