They require the incident to occur in a very specific place for the crossovers to provide any benefit at all.

Say a train is stopped on the Local between Ashfield and Illa Jn waiting for an ambulance, police or has failed. If anything had left Strathfield behind it which is not unusual, it would now be stuck. It has happened more than once. Granted, that alone does not make the crossovers viable, but it was a case where the flexibility came in handy.

To suggest that they were worth sinking millions into each year for a "just incase" scenario is madness.

Again, I don't think anyone was under the illusion of that infrastructure winning the viability argument in 2013. When proposals like that are made all options are examined, cases are made to support each, they are judged and a decision is made. It doesn't mean the other options are 100% madness, they just aren't viable given the network priorities. Obviously at some point in the past they were viable or they would never have been built, but no longer. The whole layout was reconfigured around 1983 so they were still viable back then.