It's far beyond that. They submitted that warrant knowing it lacked probable cause. And this is almost certainly not the first time they've done so; they knew which judge to submit it to. This is just the first time it happened to arise to national attention.

This is not the fault of one incompetent jurist. It hints at much more widespread corruption, probably going back years.

Any healthy ecosystem will evolve relationships over time. There's no fundamental anti-collusion mechanism in the LE machine! On the contrary, it's a state attractor within the system of incentives and organization structure of Enforcing Law under the USG.

The Bureau of Suffering, if you will.