Many developers "in their right mind" did exactly that. For a pretty long time, this was the way people manipulated spreadsheets in an automated fashion unless you wanted to buy expensive products from third-party vendors.

So many people do that Microsoft keeps a knowledge base article about it:

http://support.microsoft.com/kb/257757

"We don't recommend or support it but because you want to do it anyway, here's what to consider to make it work less badly"