There is probably a long tail of bad outcomes that could arise from admitting illegal activity on the web. But I don't think it stands up to the kind of cause-and-effect that'd be like:
IF you say on a forum, "I broke this law," THEN you get an email from hello@police.com saying, "You spoke and we listened!"
I had an email about an iPod Nano. More than happy to talk to Apple about it, but when I emailed them in 2010 about the scheme my friend was running, I never heard anything back.
I don't think simply being in the room with someone committing a crime, even knowing that's what they're doing, doesn't give you accomplice liability. I think you have to assist or encourage. You do not generally have an affirmative responsibility to prevent people from committing crimes.
As always with the internet, “the stories and information posted here are artistic works of fiction and falsehood. Only a fool would take anything posted here as fact.”
IF you say on a forum, "I broke this law," THEN you get an email from hello@police.com saying, "You spoke and we listened!"