Joel talking about what people used Excel for seems very similar to Clay Christensen's concept of hiring products for specific jobs.[0] I wonder if this was a conscious thing on Joel's part or it's a case of convergent evolution.

[0]: http://hbswk.hbs.edu/item/6496.html [edit: here's a fanastic, transcendent presentation by Christensen: http://gartner.mediasite.com/mediasite/play/9cfe6bba5c7941e0...]