Thank you! I suspected that the most likely answer was that this feature serves a blend of purposes. I wish I could find some sort of historical record of the d

Thank you! I suspected that the most likely answer was that this feature serves a blend of purposes. I wish I could find some sort of historical record of the different decisions that went into this pattern, but I understand that those sorts of gradual design evolutions tend to come about in the small, and may not have been individually recorded.