Current number of people with internet access: 1,000,000,000
Median number of employees in a Fortune 10 company: 300,000
The ratio is roughly 3000:1.
Three orders of magnitude.
Just like when you move from the realm of the atom up to the scale of a cell the rules of the road are different. I'm not claiming the difference in scale between internet and intranet is the same as that from atom to cell; there are about 10^14 atoms in a cell, what I am pointing out is that when you move between systems with three orders of magnitude difference in size, the rules are going to change.
I've referenced BigTable a few times recently. As you look at Google, and now eBay, you see they aren't using traditional relational databases, or if they are, they aren't using them in a traditional manner. This isn't an aberration, nor is it a case of NIH, these are the artifacts of working at a different scale, and more importantly, you should expect to see the differences continue to grow as the ratio widens.
At some point in the past rolling out an application to 300,000 people was the pinnacle of engineering excellence. Today it means you passed your second round of funding and can move out of your parents garage.