Explanation:
Mealy and Moore machines change their states every clock cycle.
In the case of Moore machine, the state determines the output, so it's easy to model a D flip-flop with it, where you have two states, one outputting 0, one outputting 1, and those switch based on what was the input during active clock edge.
In the case of Mealy machine, the output can change as the input changes. By an easy translation from Moore's machine D flip-flop, you can end up with one state that passes forward the input - again, constantly updating the output - without changing it, which means that you end up with, basically, a wire.
