Nice post, guys. Would you mind saying what you mean by 'lurking'? In all my life on the Internet, it's a positive thing when joining a community. You're invisible to everyone and just read. Why should people not do this? It seems harmless to be in read-only mode.
In the sense used here, "Lurking into someone's thread" means sending an unsolicited comment to a thread you were not an expected participant on.
This is something we're broadly supportive of but which, if done poorly, can be socially contentious. You could imagine pathologically bad examples like "Hey thanks for working on this project for the last 8 months, but before you ship it, just wondered if we had considered adding a teal bikeshed? Taking the liberty of CCing seven people for their thoughts on the bikeshed you'll be building."