This picture shows a lot of wires but, instead of getting all tanged up they are neatly placed on a fine wood board. There are some things bad about a circuit. Like they aren't as strong as a wire, but they are more compact than wires.

There is a circuit in my PC imagen if all of those wires in that circuit where just regular wires. That would make my PC very big but I'm not saying wires are bad. They are used in houses to carry high power. A circuit is just for sticking many wires together.