I'm still using two Panny Plasmas, one 15 years old and the other 13 years old. My LG OLED is four years old. None of them have a lick of burn in. So I am tempted to regard it as a myth.
If you use it for a variety of content, rather than a single program (like CNN) or a single game with static graphics, then your real world results match exactly what the website testing concluded...
we don't expect most people who watch varied content without static areas to experience burn-in issues with an OLED TV.
These also aren't the 'newest' OLED displays, which continue to be a bit better about avoiding burn-in issues.
The point is, that some people DO run OLED as their desktop PC monitor, and it's NOT a good thing for those people. They are just as 'real world' as your use of the TV to watch varied content.
I used my plasma for gaming at times, but it was a few hours here and there. So, I have always been in the 'variety of viewing' camp. But, there are definitely people out there who dig into gaming really hard. They play the same game for 50+ hours. So, those people absolutely must be aware of the potential issues.
But, there are extreme cases in use with the testing to show what a place which may playback CNN all day would end up with. Fortunately, most of those people use LCD displays, not OLED. So, not much chance of pixel retention with them.
I think the test was excellent because the results they stated were EXACTLY what you said the results should be with a variety of content. Anyone looking to prove burn-in is real can say "LOOK!" - but those would be some pretty ignorant people. Yet, as a commercial integrator, I would never recommend a OLED to a typical client who might very well throw CNN on the screen 24/7 at maximum brightness for a year or two... Then complain when the image got burned into the screen. I can use this to help them understand what WILL happen if they follow such a course of action.
In the home, it also helps to use something like this to emphasize the importance of just showing a variety of content, and not worrying about showing a few football games on the weekend, if you mix it up with some more normal viewing during the rest of the week.