It's not RGB that is "broken", it's the typical RGB color space used in practice, sRGB and similar, is "broken": because they are not in linear space.
The value of your nominal R,G,B number is the result of using the original "intensity" (brightness or similar) and then raise it to the power of gamma (typically 1/2.2). The purpose of this is to give more "bits" around lower end (darker end) where human eyes are more sensitive [1]. If we don't do gamma and have relatively low bit depth (like your typical 8-bit), it's very easy to produce banding at dark gradient areas.
Up to this point, there is nothing wrong.
However, if you want to average two colors (which affects almost all the operations that can happen on bitmap images, including gradient, blending, resizing, blurring, etc...), the correct way, just like real-world physics, is to average them in original linear form/value; but most of applications/implementations, as shown in this page, are just averaging their nominal "gamma'd" values.
[1] There is often a common belief to say that the introducing of gamma space historically was because of how CRT screen used to work (the relationship between electricity intensity and brightness etc.). But most of in-depth articles about this topic say that's just a coincidence.
Wow, yeah. I have done some hobby work with digital colors and rendering and I had no idea how used to the visual artifacts from math done on sRGB values directly I was that I just assumed a "fancy" transformation. Thanks for the insight.
The value of your nominal R,G,B number is the result of using the original "intensity" (brightness or similar) and then raise it to the power of gamma (typically 1/2.2). The purpose of this is to give more "bits" around lower end (darker end) where human eyes are more sensitive [1]. If we don't do gamma and have relatively low bit depth (like your typical 8-bit), it's very easy to produce banding at dark gradient areas.
Up to this point, there is nothing wrong.
However, if you want to average two colors (which affects almost all the operations that can happen on bitmap images, including gradient, blending, resizing, blurring, etc...), the correct way, just like real-world physics, is to average them in original linear form/value; but most of applications/implementations, as shown in this page, are just averaging their nominal "gamma'd" values.
[1] There is often a common belief to say that the introducing of gamma space historically was because of how CRT screen used to work (the relationship between electricity intensity and brightness etc.). But most of in-depth articles about this topic say that's just a coincidence.