Why are Americans afraid of S-300 missile systems

Why are the Americans afraid of the S-300 PMU-1 (S-300) anti-aircraft missile systems - we read about it below:

The S-300 PMU-1 is a mobile multichannel anti-aircraft missile system S-300 PMU-1 designed to defend military and industrial facilities from massive air strikes, as well as to create the country's air defense lines. The system ensures the defeat of modern and advanced aircraft, cruise missiles, ballistic targets and other air attack weapons flying at altitudes from 10 m to the practical ceiling of their combat use in conditions of intense opposition.

The S-300 PMU-1 anti-aircraft missile system includes 83M63E controls and 8 self-propelled launchers (SPU). The self-propelled launcher is produced in two modifications: 5P85TE - a semitrailer on a three-axle KrAZ-260 vehicle and 5P85SE on a four-axle MAZ-547 or MAZ-543M vehicle.

The anti-aircraft missile system has a short reaction time, a high degree of automation of combat operations and a high fire efficiency. It can simultaneously fire up to six targets with up to two missiles aiming at each target, which sharply reduces the target's ability to avoid being hit by performing an anti-missile maneuver. Without preliminary preparation of the position, the funds can be deployed in 5 minutes.

Video of S-300 missiles hitting targets