To the extent that it's a signalling move, I think it's more intended to signal virtue than tribal affiliation. That said, I'm generally willing to take it at face value, as either an attempt to minimize the depth of indirection in the conversation, or to encourage people to speak who would otherwise stay silent because what they have to say might be offensive.

I haven't noticed it make much difference either, but it doesn't follow that the person declaring it didn't intend it to make a difference... Crocker's Rules being a constraint-definer on others rather than oneself makes it necessarily a cooperative endeavor.