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.
Check the "starfield" test: https://www.youtube.com/watch?v=MVSQTHYZXD0&t=715 - the LG OLED TV shows all the stars on a perfectly black background, the Sony LED TV shows all the stars, but the background is not perfectly black. The TCL MiniLED TV shows near-perfect black background, but is missing most of the stars!