That’s true. But if you look into the test, it includes monitors and has them showing footage with static elements.
At the 6 months mark, which is aprox. 2.5 years real life usage according to RTings, the monitors barely had any burn-in according to RTings - Although I couldn’t see any burn-in. If you compare it to the non-OLED TVs at that mark, many of those had very noticeable uniformity (and other) issues.
So according to this test, the monitors are already doing better than LCDs.

Other than the Samsung S95C which is the newest model in their test.
16 months of extremely intensive tests which isn’t how you’ll use these IRL. Which is why they refer to it as “accelerated longevity test”.
If you’ll read a bit more about the test and the results, you’ll see that all of the LCDs there are also having other permanent issues.

According to them, if your usage includes varied content, burn in won’t be an issue.
If you don’t, reading more about the test and about specific monitors / TVs you’re curious about will give you a better idea.

Have you seen RTings’ articles about this?
Like: Real-Life OLED Burn-In Test On 6 TVs
Seems to really depend on your usage, and newer ones are even better according to their latests test: Longevity Burn-In Test Updates And Results From 100 TVs