The issue is probably volume. Very few applications need a resistor that's exactly 66kΩ, but a lot of applications need resistors that are in the ballpark of 68kΩ (but nobody would really notice if some 56kΩ resistors slipped in there).
For every finely tuned resonance circuit there are a thousand status LEDs where nobody cares if one product ships with a brighter or dimmer LED.
For every finely tuned resonance circuit there are a thousand status LEDs where nobody cares if one product ships with a brighter or dimmer LED.