Are RX-only iGates bad for the network?

From 2E0RLZ-10: My APRS iGate. Comments are welcome via email.

Some people say if you run a receive-only iGate, you are breaking the network by obstructing two-way messaging and even being a 'jerk'. Other people say that this doesn't happen because if there are transmitting iGates present, additional receive-only iGates can only improve messaging performance.