I personally experienced the effects of decentralization of IT as a customer of an insurance company.

The decentralization of its IT function resulted in multiple customer databases. Since customer-numbers varied, the enterprise was not able to spot customers who bought from multiple business units.

One day, the Specialty Automotive business unit cancelled the policy covering my vintage sports car, saying they were no longer interested in that type of business.

Annoyed, I moved all my insurance to another company -- the policies for my other cars, my home, my personal liability umbrella, and my corporation.

Of course, they never knew this. Because their customer databases were fragmented among their business units, they knew me as a few discrete policies, not as one customer with diverse needs.