Center pin reels, or a version of them, were likely the first reels ever made. In their simplest form they are nothing more than a spool to hold line on a shaft. They are remarkably free spinning and have no drag system (The Online Fisherman)

In 1894, centrepin Reels were first documented and introduced by Samuel Allcocks in the UK. From the UK to North America, centrepins have evolved into a major tool for float fisherman and have been used religiously for the past 50 years or more for Salmon and Steelhead throughout the province. (Sea Run Fly and Tackle)

A centerpin reel allows the line to come directly off the large spool. This makes it easier to control the movement of the float in the current. (The Complete Fishing Manual)