Just Cuz wrote:

Is there a good reason for not using emitter stabilizing
resistors and ac by-pass capacitors in 100 watt output or more RF
transistor amplifiers?

My hunch would be that most of those amps probably use ballasted emitter transistors
which mitagates the need for an emitter resistor. That, plus the fact that any impedance
in the emitter lead is an invitation to oscillation, and obtaining a good low Z bypass is
tough at HF especially at the current levels involved.

Bob WB0POQ