One of the most important roles that any NBA team hoping to at least flirt with competence has to fill is that of backup point guard. You need a steady presence who can be trusted to distribute the ball, execute the game plan, and helm the ship when the starter rests or falls to injury. Without such a player, a team runs the risk of being cast adrift for long stretches of both games and potentially even seasons.
Because of this importance backup points tend to get paid, which makes their acquisition all the more difficult to navigate for franchises.