I would really like to understand where that "sometimes" is, nowadays.

RGB just means that color is expressed as a triplet of specific wavelengths. But what is red? And what does red = 1.0 mean w/o context (aka primaries & whitepoint)? What about HDR? What does green = 2.0 convey? Etc.

For context, I worked in VFX production from the 90's to the early 2010's. About 25 years.

And in commercially available VFX-related software, until the early 2000's, mostly, RGB meant non-linear sRGB, unfortunately (or actually: "whatever" would be more true).

And it shows. We have VGX composed in non-linear color space with blown-out, oversaturated colors in highlights, fringes from resulting alpha blending errors, etc. A good compositor can compensate for some of these issues but only so far. If the maths are wrong, stuff will look shitty to some extend. Or as people in VFX say: "I have comments."

After that, SIGGRAPH courses etc. ensured people were developing an understanding on how much this matters.

And after that we had color spaces and learned to do everything in linear. And never looked back.

Games, as always, caught up a decade after. But they, too, did, eventually.