Some businesses use Microsoft Office for business processes that go far beyond Mail-Merge, but are essentially unknown to people who don't work for large corporations. Have a look at the half-dozen Microsoft Office programs you've never used, and that many people have not even heard of.
This is one reason why it took Munich a whole decade to switch most (but not all) users from Microsoft Office to OpenOffice, and they probably lost a ton of money on the switch (ie if you honestly counted lost productivity, which I'd bet is still being lost).
I'd also guess that a German city's use of Microsoft Office is probably pretty trivial compared to an American Fortune 50 corporation.
If someone wants to do a PhD on this, I'd love to read it ;-)