The disadvantage of using a voltmeter and ammeter on circuit measurements is that internal burden in both these instruments can affect circuit operation so much as to make a measurement useless.
A voltmeter is used to measure units of electrical pressure, and an Amp meter is used to measure the amount of electron flow (AMPS), through a circuit.
You could stab or hit your finger and it could swollen or bleed.
They rust over time.
They are smooth and over time can work their way out of the wood.
They can split the wood when being pounded...