>The messages ARE evidence for a case. They are the proof that a crime happened. The problem is that they don't tie the defendant to the acts.

Yep,

So they have a cop stand up in court.

"We read X messages" (Here they are look how exceptionally heinous they are)

"We then asked the service for the IP."

"We then asked the ISP to deanonymise it. "

"Heres the guy we found at that IP"

He signs a stat dec that using his brilliant super techno crime brain he has correctly attributed the messages to this human.

It sounds like the defense from there was: But your honor, there's no history of these messages etc etc.

Judge is not technically capable of reviewing the evidence. Defense probably not technically capable of reviewing the evidence either. Prosecution probably not capable either. They are all just playing out parts really.

After probably having dealt with hundreds of these, on the balance of probability like most courts do they just backed in the statement by the cop.

The end unless you can find some way to challenge the technical evidence. Which he did after some time.