While you make a good case for radio, there have to be cut-off points, at which techniques must be considered obsolete, not to burden educational systems and students unnecessarily in perpetuity.
While having the skill is a 1 or a 0 (either you know how to use a radio with some proficiency or you do not) the use cases for older/simpler technology get fewer and fewer gradually.
At which point can a system no longer afford to support technique x? Of course, it depends on the system but you are probably not going to wait before the probability hits 0 if you care even slightly about being efficient – but it's never an easy call to make.
While having the skill is a 1 or a 0 (either you know how to use a radio with some proficiency or you do not) the use cases for older/simpler technology get fewer and fewer gradually.
At which point can a system no longer afford to support technique x? Of course, it depends on the system but you are probably not going to wait before the probability hits 0 if you care even slightly about being efficient – but it's never an easy call to make.