Gamma correction should only be applied,if wanted, on the final render image. Applying GC in internal rendering stages produces unreal and not physically correct results.

For example, if you combine two textures t1^g + t2^g is not the same as (t1 + t2)^g or (t1^g + t2^g)^1/g will not give t1 + t2

Stupidity also evolves!