What is with the 'reply all' button.

We have about 200 people in my office, then we are part of a UK company that has about 1000 people. Then that company is part of a global team that has about 50,000 people all over the world.
So today, some douche bag in Canada forwarded on an email and hit 'reply all' so this went to the entire global network group email address by mistake.
Have you ever got an email that was not meant for you?
I have, I deleted it and forgot about it.
But that is not what the 50,000 people who wok in my company did. no, no no, they decided to hit reply all and tell everyone that the email they received was not meant for them.
So one by one the reply all answers came in. From all over the world. 100's of people wrote back replying to all and seriously this went on for hours.
I am sitting at my desk, just deleting, deleting deleting.
Then someone wrote a reply all, saying that the whole global network is copied in on the email and to please stop replying all....then more people reply!!!
And to think,that when all the other people on the other side of the world who are currently asleep, when they wake up they will write back to the first email replying all because they would not of yet read the email telling them not to reply all...oh the pain.