There is actually not a ton of talk about this. There was a video I saw about LG out of the box needing some time to self-calibrate. There is also some talk about a firmware patch which fixed black crush as an issue.
There is little talk about actual black crush being a serious issue with OLED. Unlike blooming, which anyone can see rather easily on a regular basis.
There is also, apparently, a discussion on AVS about this being an issue and how it was resolved by LG.
OLED is capable of excellent black levels. The best since the best plasma displays. But, there is very little actual fact supporting black crush as an actual issue of the technology vs. an issue with a specific display/processing setup from the manufacturer.
There are tons of very high-level owners who would be complaining and this would be front level news and information.
Here's a great video that brings it up, discusses it, then talks about how the issue was entirely resolved by someone who does care a great deal about video quality: