I am not a fan of Golang or the approach taken to designing it, but I will say, that writing code in a certain way may even have zero cost, because after some time it may be natural to write code that way to someone. For example this works for programming paradigms. I am just as familiar with FP as with OOP and when writing FP code I avoid mutation. Does that make my code writing slower? Only in so far as a problem inherently is or is not more difficult to solve without mutation.