Your way of thinking is so different !
capacitor must has TWO CONDUCTIVE PLATES as the charge can go through it and store in the dielectric medium.because,if there is no conductive plates, then that nonconductive plates will work as dielectric medium. and i know that in circuit, you will connect it by wires. which has low surface area. and that will be consider as the surface area of capacitor. which is so little and , by this equation, your capacitance will be,C=e A/d will so so so little, you also know that there is already so less capacitance we are having. in practical it is in uc!
in eqaution, e is permittivity,A is LARGE plate area, d is SMALL distance between plates.