Damaged engines just don't pick an idle condition to reside by themselves. Something has to command them there and then latch them at that condition.
Goose bits clogging the air passages reduces the airflow. It doesn't matter how much fuel is going into the cans as no more fuel will be consumed than there is O2 to support the combustion thereof. The analogous piston engine case would be carb ice instead of goose bits.
The compressor blades likely do a decent job of cuisinarting, but the stators get in the way while the passage shrinks 30:1. Remember that air is compressible while solid bits and liquids are not.