I have never heard proper reasoning for squashing commits. I don't think sanitized history is useful in any context. Seeing the thought process that went into building something has been repeatedly useful in debugging things. It's also useful to me as a software engineering manager to help folks on my team get better. I could care less how "pretty" git log looks, but I care a hell of a lot about what git diff and git blame tell me. They help me figure out where issues actually are and how they came to be.