Part of the Bob's argument was that the function was not just doing a replacement, but also a ensuring the replacement was only done once. Essentially, there's

Part of the Bob's argument was that the function was not just doing a replacement, but also a ensuring the replacement was only done once. Essentially, there's state maintenance in there, which complicates things, hence the original post about extraction. Extraction provides descriptions to the state maintenance. I would agree this particular post is taking abstraction to an unreasonable level, but that is definitely a subjective analysis.