The problem is that the LCD technology only allows manufacturers to keep pushing up the brightness, without any help for the darker areas of the screen - in fact they can get even worse than they already are, because the backlight is pushing so much more light through. You lose a few stops of darkness, for fractions of stops in brightness. So the OLED might not be able to get 100% of the info that is coded to HDR 1000+ by a few percentage points, but LCD can never get the info encoded in the darker places, and the difference there is in orders of magnitude.
Not always.
VA panel have deep blacks that looks black in a room with normal light.
At least according to my experience with my Samsung that now I forgot the series.
I think the contrast ratio is 1:3000 or 3 :4000.