... but only "sometimes"

This is an article I saw somewhere else, and the author explains it in the video:
https://www.shutterbug.com/content/s...r-photos-video

He's saying that in some cold weather situations a lens hood can significantly soften images.
The salient point is about 3:30 into the video, but it's only a bit over 4 mins long.

- And don't forget where you tossed your lens hoods