For interpolation, averaging, etc. anything based on RGB is not going to give good results. For example, if you average pure red and pure blue, you should get something like pure purple. But if you do that in RGB you'll get #7f007f, a much darker color than either pure red or pure blue. If you do it with LAB, you'll get #ca0088, which is perceptually about as bright as either of the colors you started with.
It helps to use linear gamma when manipulating RGB values. Linear gamma fixes most issues with interpolating and mixing RGB values and that’s also why most modern CG pipelines use it. It produces the most natural results.
Yes linear gamma generates the most natural results, because that's the way physical light combines. Gamma was a great invention for display and transmission but it sure wrecked our ability to mix colors.
