In my old profession before I retired, if someone did not seem to have a grasp of the obvious we would ask them, whatareyounew? With avent of index shifting there has always been a need to adjust derailleurs on the fly. With the new through the frame routing, the adjusters on the downtube cable stops (or the cable stops themselves) have been removed so in-line cable adjusters took their place. For on thing, without the front in-line cable adjuster, there would be no way to fine tune the front derailleur at all. And once you get some mileage under your belt, you will learn that your once in a blue moon is more like every other week. Most derailleur drivetrain issues on newer bikes (especially those that route through the frame) are a result of cable routing; especially with Shimano and Specialized frames. Good luck with your riding and I'm sure in a short time you will realize there is an advantage to be able to adjust your derailleurs while riding.