iirc the main reason for QOI was to have a simple format because "complexity is slow", so by stripping things that the author didn't consider important the idea was the resulting image format would be quicker and smaller than something like PNG or WebP.

Not sure how well that held up in practice, a lot of that complexity is actually necessary for a lot of use cases (e.g. you need colour profiles unless you're only ever dealing with sRGB), and I remember a bunch of low hanging fruit optimisations for PNG encoders at the time that improved encoding speed by quite a bit.