This is correct, but ambiguous.  What, exactly, was the reason?<p>The 90&#x27;s client-server model involved fragile, proprietary stacks of non-portable client software and proprietary protocols.  That model would have you &quot;install&quot; Google, Facebook and Amazon as separate applications.  Ironically this has reappeared as &quot;apps&quot; on portable systems; it seems we&#x27;ve figured out how to make this work in constrained environments.<p>I have been solving some internal admin problems with a &quot;two-tier&quot; framework; ng-admin + postgrest.  The business logic lives in PostgreSQL stored procedures and triggers.  Effectively the middle tier has merged with the database so a big moving part has been elided from the stack.  One nice benefit is that the cost paid to implement business logic produces a database model, not an arbitrary accumulation of inscrutable middle tier `behavior.&#x27;  The REST API simply reflects -- and is always in perfect alignment with -- the database model.