Agreed - but only where it makes commercial sense to, and each of the layers of the company's IT platform may end up with different plans for integration and end goals for it.
You probably don't want 10 different desktop hardware providers and IT support systems, but it might be a bad idea to try and unify the trading systems for slightly different looking business units unless there's some competitive advantage to be had by doing it.
There wasn't a CIO at Deutsche when I was there, it all fell under the remit of the COO who was this guy:
https://en.wikipedia.org/wiki/Hermann-Josef_Lamberti