I've been on LinkedIn for a while, without engaging with it that much. In the early days, if someone sent you an invite to connect, there was an option "I don't know this person," with the implication that they would be somehow censured for spamming someone they didn't know.

That option is long gone, but I don't know when it disappeared. Does anyone know when this happened? If anything, that's a sign of when it jumped the proverbial shark.