[bscphil]

> You seem to be confusing bit's with stops of dynamic range.

This is correct, they seem to be mistaken. I've seen this mistake many times in this thread. I wrote a comment in reply to one of them explaining in some detail what the point of higher bit depths and "HDR" (as a set of technology standards) is: https://news.ycombinator.com/item?id=24044818

[formerly_proven]

Your remark (~"x bits worth of luma doesn't necessarily correspond to x stops of DR on a display") is entirely correct but is tangential to my point. You can't encode a scene with more than 8 stops of dynamic range into an 8 bit JPEG without either loosing details or performing a tone-mapping-like process.