MB-6582 Encoders With Integrated Button

[Doogy Rev]

Is there any advantage to using encoders with built-in buttons? I noticed there are tracks on the MB6582 PCB for them and they are all combined into the same input. Is it just another shift button or what function does this serve? Is it worthwhile getting such encoders? If it isn't worthwhile, could those tracks be used for encoders with illuminated shafts instead?