Not quite. I have worked with sap at many different clients. Some Reasons for buying SAP ( by that i mean their ERP as well as funxtional or industry specific tools and applications.) are as follows
Scale: at this size, you pick SAP or Oracle. There's very little else out there in the market.
Proven implementation: speaking for most clients, you cannot get a major ERP implementation done without outside help. You will turn to either the vendors or major integrators. You will then ask them to give you advice and prove their expertise. They will give you a list of prior successes, which is in my sector always going to favour SAP as Oracle have a bad track record. You will then pick the system and configuration and maybe even architecture they are recommending.
Industry Expertise: SAP, in many industry sectors, know their shit. You can try making your own tools, you can try pulling 20 different apps together to get the functionality you want. But that increases cost, complexity and often violates architectural principles. So you just buy SAP and all the modules, because they have every possible business process mapped out, data structures configured, suppliers and product catalogues ready to go, etc. Oracle has this too, but fewer products support or integrate well in my limited experience.
Of course, SAP isn't without its issues or drawbacks, but i have consulted with clients across many projects including the initiak upstream business cases, and these are often the key deciding factors.