making the dangerous assumption hat no poster has actually been near to a GT either as rider or staff...Nobody can race hard for three weeks. All riders and teams have off days, get ill, have a "jour sans", during a GT. It's just how things go. Hence a few transition stages where either the sprinters come out to play or a break gets home are fine. Simple fact - GTs are won in ITT or mountains. So a GC rider has to be a competent climber and decent ITT rider, able to sit in on the other stages, look out for what's happening, and be surrounded by a good team. A rider can be best there is, but no team support = no wins or even likely podiums. The big gains for a GC rider are ITT or mountain finishes, that's where it all happens and why sprinters don't win GTs. They have their own opportunities in flatter short stage races and one dayers.
The radio thing is spurious, a sport director can yell all day into the radio but if there are no legs available to do what he wants, it's all pointless.
So we have different riders, GC riders, opportunist rouleurs who mught grab a win on a transition stage, sprinters, domestiques doing their best to do their job and then get in before the elimination. Team sport, and all that, and far more complex than it appears at first sight, with many unwritten protocols that are broken at peril.