Biasing is necessary in a transistor circuit to keep the transistor working. Without proper biasing, the circuit will fail

of course stability of self bias circuit is much greater than fixed bias circuit

low input impedance

It is a bias of a fixed voltage supplied by a separate low-power bias supply. Early radios used a 9 v tapped bias battery. In some amplifiers fixed bias can be dispensed with and the bias voltage is derived from one of the currents in the circuit.

Why do you consider it neccessary to bias transistor?