Comment by bob1029

Actual film grain (i.e., photochemical) is arguably a valid source of information. You can frame it as noise, but does provide additional information content that our visual system can work with.

Removing real film grain from content and then recreating it parametrically on the other side is not the same thing as directly encoding it. You are killing a lot of information. It is really hard to quantify exactly how we perceive this sort of information so it's easy to evade the consequences of screwing with it. Selling the Netflix board on an extra X megabits/s per streamer to keep genuine film grain that only 1% of the customers will notice is a non-starter.