It has nothing to do with the cloud. The problem here is that Vendor X really has no incentive to create interfaces to communicate with Vendor Y, beyond a customer willing to pay them to create said interface. And even then, the customer is only paying Vendor X, and not Vendor Y, so any assistance Vendor X gets from Y will be spotty at best.
And nothing about that is going to change until the federal government steps in and forces these vendors to play nice using a set of standards. It's a slow, messy, ugly, wasteful, and frustrating process, but it is the only way this problem is getting solved.