The quote I mentioned is just a quote, but it points to a part of a reason. If you are a CEO or a high level executive of a big company, going with IBM or Oracle is a safe bet. It's not very likely you will be blamed for failures of IBM or Oracle. It may be a money hole and bad for business but it's a much safer bet than going with some smaller vendor instead of big name vendors.
The "nobody got fired for buying IBM" thing expired decades ago, that mantle passed on to Microsoft. Last 5 - 10 years, nobody gets fired for architecting dozens of microservices in the cloud.
