it's possible that freight trains are waiting for an Amtrak that was itself, earlier delayed by freight trains and became late. And given that equipment on a route will become the return journey this could cascade out of control.

Amtraks are never in charge of dispatching on routes they don't own, and there's a very clear correlation between on time performance and percentage of the route they do own.

Possible, but all I ever see is finger pointing and I don't trust either side to be telling the full truth.