Which just illustrates that while comparatively young companies may all be all about one application, its not exactly unusual even for a company that starts out that way to rapidly grow into one providing a large array of applications with overlapping use of data.

While there are reasons that running all those applications for, say, Google on a shared RDBMS backend isn't the right answer, the reason isn't that Google has a single application that uses all its data and so doesn't have to worry about coordination between different applications using the same data.