I think I get it better now but I’m still not finding why keeping the whole comment in a commit message is better than in the source code. If it’s in source, I

I think I get it better now but I’m still not finding why keeping the whole comment in a commit message is better than in the source code. If it’s in source, I don’t need a context switch to read it, I can improve it (e.g. if the wording was ambiguous), I can easily extend it without asking people to read commits X, Y and Z in order. What’s the advantage?