A large conglomerate I used to work for used Oracle for its finance systems. Oracle pushed to move everything off premises and into the cloud.
All whilst pushing its next gen all singing, all dancing "drill all the way down into invoice line items from a single figure on the P&L" wizardry.
Except even their fastest mega server couldn't really handle the volume of data. I left the company at that point.
After buying another large conglomerate that uses SAP, last I heard was, they were going to migrate the whole lot to SAP.
Either it'll all go Tits-Up, or they'll still be trying to merge the two in 5 years time, or they'll give up and will still be running the two side by side 10 years from now.
You heard it here first.