Someone who wants to be able to see the screen during the day when there's sunlight in the room, or someone who wants to be able to see the full spectrum of visual fidelity during a movie.

Its not like you're going to have a blank white image on screen all day, but if you want to accurately portray the contrast between say, the shadow of the jungle, and the bright colours of a bird that has sunlight glinting off it, then you need to be able to have the brightest parts be very bright and the darkest parts be very dark, because that's what reality looks like, the outdoors gets brighter then 100 nits.

My old projector doesn't even have anyone knitting in it but it smells like grandma.