How does SiP Module differ from the scheme of DCA

Use SiP (System in Package) Module rather than the scheme of DCA (Direct-Chip-Attachment):
1) If system-maker obtains Known Good Modules from module vendor,
•he can reduce system defects-per-million
•he can reduce system test-time
2) If system-maker obtains Small Form Factor Modules with Low Profile from module vendor,
•he can reduce the occupied area of the regarding circuits without sacrificing the thickness of them