There's nothing inherently wrong with darktable and RawTherapee and such having tons of choice in image processing, but I made Filmulator "opinionated" because among open-source photo editors it's an unfilled niche.

As far as filmic versus Filmulator, both of them can compress highlights while retaining colors, but Filmulator does it by simulating the depletion of developer while filmic has a whole bunch of math to maintain hue and saturation while rolling off the highlights pleasingly. Filmulator also enhances local contrast, which as far as I know filmic does not.