As a former high end audio/video salesperson, I just want to state for accuracy that local dimming, as a feature, is not dynamic contrast. Dynamic contrast is terrible. By having an LED backlight array dim spots that are darker in the source material, the display achieves better absolute contrast. It is not adjusting the exposure to fake it. It is instead getting closer to the contrast given by the source material. It created some halo issues, but it was a step in the right direction.
This is not new tech at all - I was selling Samsung LED TVs with this feature in 2007 or so. Samsung, Sharp, and Sony has little choice but to improve contrast, because their LED sets were right next to Pioneer KURO plasmas that were just absolutely amazing - OLEDs are only catching up their PQ now, 15 years later. First on the scene was the Samsung LN-T5781 - https://www.cnet.com/reviews/samsung-ln-t5781f-review/
Seriously. Imagine people going out and proudly buying a shiny new MiniLED TV only to have their half-educated HN jockey of a child come in and disable the entire point of that technological advancement.
Even normal LED backed LCDs can have FALD (Full Array Local Dimming for those who don't pay attention to this field) and that's not especially new, though, hit or miss in effectiveness on earlier TVs.
Eh, depending on the size of the dimming zones, the halo can be much worse than the shitty LCD contrast it is trying to improve. At the extreme you have edge-lit displays which is just 100% useless at improving the contrast in any realistic scene while introducing very noticeable giant halos for mostly-black screens. You can get used to global shittiness but local and temporal artifacts will always stand out.
It's all just an ugly hack compared to real emissive display technology where each pixel can be set to any value on the full brightness range individually.
This is not new tech at all - I was selling Samsung LED TVs with this feature in 2007 or so. Samsung, Sharp, and Sony has little choice but to improve contrast, because their LED sets were right next to Pioneer KURO plasmas that were just absolutely amazing - OLEDs are only catching up their PQ now, 15 years later. First on the scene was the Samsung LN-T5781 - https://www.cnet.com/reviews/samsung-ln-t5781f-review/