alt Hacker NewsSome are more used than others, and indeed, JPEG is an initialism. My point is the uppercase treatment doesn't depend on initialism, i.e. RAW doesn't have to stand for something to be capitalized because uppercasing file extensions is just a thing that happens.
The way I interpreted what they were saying is that they were focused more on the fact that for raw files, the extension is not ".raw", it's ".nef" (for Nikon for example) so that's why it's questionable to capitalize it.