Does magnetic anomaly detection still matter?

Has magnetic anomaly detection gone out of use in maritime patrol aviation?

Only partly. MAD repeatedly falls out of favour when operators decide they no longer need it, then later returns to use.

The answer is qualified because magnetic anomaly detection repeatedly drops out of use and then returns. When operators decide they no longer need to bother with MAD, later experience can restore its place in the patrol-aircraft sensor suite. Its role is cyclical. A detection method may be downgraded without becoming permanently irrelevant.