snark aside, just because a logical fallacy exists in an argument, it does not mean the argument is untrue. My experience echoes jedburg's - services should maintain their own datastore and provide api access. This allows them to be decoupled and allows the service to alter their datastore as needed. When multiple services leverage the same underlying datastore, things can get overly coupled. This becomes increasingly important as organizations grow because the coupling means more overhead communicating and aligning around changes.

Jedburg is an expert because he has seen this happen in multiple companies. I have too, but I don't have the speaking/consulting breadth of experience that they have. Credentialing and appeals to authority work because we are squishy humans and we can't verify everything so we lean in on others. That does not mean that authorities are always right, but when their experience and advice mirrors other's experience and advice, there is something to it.

And for the record, in public companies (two of them), I have exactly seen this play out: a well defined api that does not allow others to muddle in their datastore leading to _single_ meetings where new functionality is discussed and agreed upon and later implemented. I have also experienced the pain of multiple teams sharing a datastore when the datastore now needs to be altered which led to dozens of meetings across several teams and a rollout plan that was measured in months and quarters due to coordination needs. I can firmly say that the latter is a much harder (and expensive!) problem to solve in each case I've experienced.