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.
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.