Serious question, why not? Do they produce some harmful flicker or something?

burn in with static ui elements - The idea is, that regular very different images reduces the risk.

So the same issue we’ve always had with crt, lcd, and plasma.

Actually a different issue. With CRTs and plasma, burn-in would actually burn an image into the phosphors of the screen.

OLEDs will slowly burn out after continued use, usually starting with the blue LEDs, giving a similar appearance, but not exactly the same (for example, you can only see the image persistence when displaying an image).

Doesn’t QD OLED fix this? Because the actual OLED part of it is only the backlight, then color filters produce the other colors