I dont think a pressure washer is an alternative for hand washing the car, its a supplement.
Its very good at cleaning the underside of the car and for instance inner wheel arches, getting the dirt out of there. Dirt stays moist.
Thats why a 90deg nozzle is a must imho
You can also remove accumulated salt after the winter pretty effectively with a pressure washer, especially if you use it with warm water.
So its a very good aid in keeping your car technically clean for the preservation of your car.
For keeping it optically clean it's indeed not super effective, maybe blowing the dirt off better out of little areas and maybe it washes out algae better out of seams, but you cant really use it up close.