From my limited perspective (ca. 10 Fortune 500 orgs) Oracle definitely is (or was) somewhere at each of these but in most cases was considered a liability rather than asset and in two cases I participated in projects migrating away from it (that were quite time-consuming because of all quirks on the way). Only in one case the org was adamant they want to keep it (I don't know the actual reasons as I was in another department but from what I understood they used a lot of Oracle-specific solutions and were depending on Orcale support a lot).