Alot of the players listed weren't signed by the Saints as UDFA so I don't see how the Saints are being given credit for "discovering" some of these guys......and only a handful actual carved out careers.
On the surface, I follow your logic. However, consider the following:
Nearly all of those guys were already on the Saints' radar; other teams signed them first. But after they were cut later, the Black and Gold eventually got their guy.