MiniLED is not "just marketing" according to rtings:
To be fair, MiniLED displays are significantly cheaper than OLED displays, but their performance isn't really comparable.
A more interesting comparison here IMHO is with panels using the same technology, sold around the same price (IPS or VA) and lacking Mini-LEDs backlighting.
Rtings seems to conclude that Mini-LEDs backlighting is far better than full panel back lighting.
Hell, I'm using one right now (KTC M27T20, paid 330 euros) and it's just amazingly good... even if not as good as OLED.
Also, right now, OLED also suffer from text fringing issues : https://www.flatpanelshd.com/news.php?subaction=showfull&id=...
So, I don't know, I guess unless you purposely display a static white element for hours every day for years, you won't live to see a burn-in on an OLED display.
The fact that it's not as good as OLED on one performance metric doesn't mean it's smoke and mirrors, it's just a middle ground technology that makes different tradeoffs.