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There are two variables I can think of for the Investigation section:
1. Deep-web: The logic from theymos is very clear about it.
The reason that doxxing has been allowed up until now is that it's occasionally very useful in scam investigations. However, oftentimes doxxing someone is used as a weapon in itself instead of a part of any investigation, and as a result innocent people are sometimes hurt. So to protect the innocent while hopefully not hampering scam investigations too much,
2. Rank requirement: It's not clear why is this minimum rank requirement that someone has to be at-least a member.
If someone like a solicitor or law enforcement were trying to linger there to see if there was anything they could prosecute over, all they have to do is pay $10 for a "reader" account of that board.
There should not be any harm since the information are actually on the deep-web.