What I do find amusing is the CouchApp advocacy stuff that calls the traditional 3-tier architecture the "bad old days" of years past. This is amusing because CouchApp is basically a reincarnation of the classic 2-tier ("client server") architecture of even more years past. A classic architecture consisting of a rich client talking to a database backend, the days 2-tier reigned supreme would also be a period 3-tier developers call the "bad old days". Of course, the rich client used to be written in something like Visual Basic or Delphi and the database would be an SQL database, but the idea and division of logic is the same. Like the classic 2-tier apps, a CouchApp would have to divide the business logic between the client and the database.