This is very true, but very not true as well.
Contrast is king. Absolute king. Period.
So, what is the problem?
The room the display is going to simply can't be ignored. Otherwise, everyone should just get a OLED and call it done. I know I would.
But, the room is incredibly important to the viewing of the content as well. If you have such a bright room that you can't see the shadow detail and the 'highlights' are barely even white in the room you are in, then it is all meaningless.
Sure, it looks great after dark, but that doesn't do much for you when you are trying to enjoy a movie at noon on a Sunday afternoon.
I had plasma for years. The undisputed king of contrast for years.
But, it was a tough go of things for those afternoon movies which I enjoyed. I would flit off to my basement to watch on my projector, returning upstairs to watch the football game later that day... and still not being all that happy as reflections made viewing really tough.
So, contrast is king, but with high ambient room light, you can't appreciate the non-existent black levels you don't really get in such a bright room when using OLED. You need a TV with the brightness to combat the ambient light in the room.
In a room that's a bit darker, without the massive windows, for sure a basement setup, then OLED is God-tier for displays right now.
But, in a bright room, you gotta deal with the realities of the space, and a good LED LCD may have the brightness to actually deliver the usable contrast during the day to allow things to be enjoyable, while still delivering solid (if not as good) of performance after dark.