To be clear here, there's a massive difference between RGB OLED (Samsung's tech) and WOLED (LG's Tech). The former uses OLEDs as the complete display; red, green, and blue OLED subpixels are directly emissive and generate the picture seen. WOLED on the other hand just uses white OLEDs, with filters in place to generate the necessary RGB subpixels.

https://www.pcmag.com/encyclopedia_images/WOLED.GIF

Traditional OLED burn-in has not been solved; blue subpixels still age noticeably faster than red or green. LG's method gets around this because there's only one type of OLED subpixel, so while it degrades they all do so fairly evenly.

The trade-off is that filters screw up viewing angles and block a lot of light, driving up heat and power consumption (this being why it can't be done on phones). The color gamut is also a bit weaker, because the gamut can only be as wide as a white subpixel, as opposed to the combined widths of separate RGB subpixels. It's a neat hack though, and while it has its drawbacks it does solve some of the biggest problems with the tech.