Guns are stupidly loud. A suppressor can literally save you from permanent hearing damage if you are forced to fire one inside a confined space.

They make guns quieter and reduce recoil. All around more pleasant to shoot and reduce hearing damage. Guns are loud enough that exposure to even a few rounds in close quarters can cause hearing damage so suppressors should be in regular use as safety devices. They don't make guns safe without earpro, they don't make them silent, they don't even make them that quiet. You will still know if one goes off nearby. This is one of the things about hollywood that pisses off everyone who knows squat about guns, and why we try to refer to them as suppressors rather than "silencers".

They are in fact basically never used for clandestine violence in places where they are legal (which is most of the US). On the other hand, there is a clear legitimate use of them: protection of hearing when you are shooting your own guns for fun, which is a legitimate activity that millions of Americans engage in every day.

Banning suppressors is kinda like as if European countries today banned possession of English longbows. These very much can be effectively used for violence, as Agincourt has shown. However, nowadays, they emphatically are not used for that, and if modern European government loudly declared a war on longbows, and went after the owners, one would think that they went crazy: shooting longbows is a pastime of medieval reenacters, not criminals.

Suppressors are legally required in many european areas, and completely unrestricted in many countries even with restrictive gun laws. They are primarily a nuisance reduction and hearing safety device. The US's strict regulations mostly stem from people watching spy movies and failing to understand that they are not realistic.

John Wick isn't a documentary.

Firearms with suppressors are still very loud (>130 decibels or about as loud as an ambulance siren) [1].

[1]: https://en.wikipedia.org/wiki/Silencer_(firearms)#Effectiven...