Insulators are used to physically separate conductors. At what point do you want your insulator to become a conductor, and short out all that it protects?
Still confused!
Insulators stop electricity. Conductors make electricity flow. On and off. Ones and zeroes. Computers.
Did you not understand the analogy of the switch?
Insulator == OFF.
Conductor == ON.
Think!
Mechanical switches transition from insulators to conductors!
Vacuum tubes transition from insulators to conductors!
Transistors transition from insulators to conductors!