Andrew Sarangan wrote:

Why not use a VOR receiver for airway navigation? Using a GPS for airway
navigation kind of seems backwards.

For one thing, GPS will keep you right in the center of the airway's
protected airspace at all times. With long VOR legs, lousy G/A VOR
receivers, and aging FAA VOR stations, you can easily depart protected
airspace on a long airway segment, like many in the mountainous west.