I have come across a circuit (I am not allowed to share it) with an opamp that uses a special output. The opamp's output is loaded with a resistor and has no other connection. It is the current drawn by the opamp that is used as output instead. This output current is then fed into an optocoupler, which controls other circuitry and feedback is then brought to the opamp's input to close the loop.
Does this solution have any advantages apart from possibly a lower component count? Are there any risks (one could be different values of supply current for different opamp types)?