Why is voltage divider bias a more stable bias than a collector feedback bias?
I have to make some assumptions about what you are really asking. There are 2 major ways to bias a bipolar junction transistor (BJT). The first is with a resistor in the emitter and a voltage divider to the base. Works great. The emitter resistor raises the input impedance and controls the gain. The second way is to connect a resistor between the collector and the base with the normal collector pull-up resistor to Vcc. Also works great. This method lowers the input impedance and controls the gain.
Yes, although the input impedance is likely dominated by the low Rbe of a grounded-emitter amp (in the neighborhood of a few kΩ, depending upon the emitter current).There is one disadvantage of the shown bias scheme if compared with the Re method (emitter resistor):
The input resistance is reduced (Miller effect)