The 18-loop pedals (or any of those ridiculously large loop pedals in general) allow you to do certain things:
-enable you to very quickly (since the switches are right next to each other) turn on or off 18 (or however many) different pedals
-enables you to switch on/off 18 (or however many) different (depending on how it is wired up) loops with different pedals in each loop (or different combinations of the same pedal set if you have multiples of a pedal)
-makes your signal completely true-bypass (for those who are sticklers for their clean tone being bass -> cable -> amp)
-the ability to not have to reach for the pedals on the back again (so long as you leave them on)
-additional lights to blind you onstage/make light shows with
