You can think of the dryer tube as being a "wire" with a certain linear "resistance" per foot. A bend would be a "connection". Each connection inserts a certain amount of resistance. This ducting resistance is due to air turbulence and a bend creates a lot of turbulence.

Similar to the starting circuit in a car, if the wires and connections insert too much resistance, you'll never be able to draw enough current to start the car - unless you increase the battery voltage.

A blower can work into a certain back pressure ("battery voltage"). Similar to an electric circuit, as the voltage drops due to the connections approach the battery voltage, there will not be much current flow (air movement).