Yes, this system does not seem to prevent the information from spreading.
I guess that the logic is that most people who know how to make a screenshot also know how to make a fake screenshot.
So, let's say that Mr A is not a very honest guy. Moreover, Mr A has a sensitive document that could be a liability in court. He wants to share it with Mr B. But, he does not completely trust Mr B. With this system, he can share it. If Mr B sends a screenshot to the police or a judge, it will be easier for Mr A to claim that the screenshot is fake.
That's just a guess... I hope that it was not the intent of the dev, though.
I guess that the logic is that most people who know how to make a screenshot also know how to make a fake screenshot.
So, let's say that Mr A is not a very honest guy. Moreover, Mr A has a sensitive document that could be a liability in court. He wants to share it with Mr B. But, he does not completely trust Mr B. With this system, he can share it. If Mr B sends a screenshot to the police or a judge, it will be easier for Mr A to claim that the screenshot is fake.
That's just a guess... I hope that it was not the intent of the dev, though.