Typically in a debate, the person tasked with proving their side is the one who says something can happen.
If you propose, for example, that the text a game is using can be changed over time, it is YOUR job to prove that. You can’t say, “PROVE IT CAN’T HAPPEN”, because that’s not nearly the same thing.
In a murder trial, the prosecution is charged with making their case. The prosecution can’t walk in, listen to the defense team and then say, “YOU CANT’T PROVE HE DIDN’T COMMIT THE MURDER, SO THERE”.
That’s not how it works. The person who makes the claim has to prove the claim they’re making.