It's interesting and often missed that this strategy implies a view of human collaboration and organization. Note that the memo says: 'All teams... Teams must... ...another team’s data store...'. It seems that someone figured out that a (5-10 person?) team is the right human collective size to design and build useful stuff, but that collective shall expose what they build to other teams via APIs. It's fine for the team to do things in a tightly coupled way - internally! In a way, tight collaboration between teammates can be reflected in tight coupling of internal components of whatever they build. But across teams the coupling shall be more formal and via APIs, reflecting looser and less powerful collaboration possible across teams.