I don't think it's a big issue on Microsoft's radar because a lot of OLED screens have a high enough pixel density that the problem isn't really noticeable. The subpixel arrangements themselves have also improved in recent years, further mitigating the issue.
I have a 27" 1440p 3rd gen QD-OLED panel and while I can make out some fringing if I pay real close attention to black-on-white text, it's not noticeable in general usage. The 4k panels have such a high DPI that I can't see the fringing at all without a magnifying glass.
If you know that your monitor is a 3rd-generation QD-OLED panel, then you probably know that text rendering was the main complaint about earlier generations of QD-OLED, and there are probably still more of those in the wild than ones as recent as yours.
This is also a very valid point. The improvement in text clarity on this panel was one of the key reasons why I decided to pull the trigger on this $1,000 monitor, while I had passed on previous models.
I have a 27" 1440p 3rd gen QD-OLED panel and while I can make out some fringing if I pay real close attention to black-on-white text, it's not noticeable in general usage. The 4k panels have such a high DPI that I can't see the fringing at all without a magnifying glass.