I think this makes sense when you think about the Super Producer era of the 00s and how many of them are inextricably linked to Jay and his brand
I wouldn't say he made them all famous. I mean....
Timbaland- already famous from his work with Aaliyah, Ginuwine, and Missy. There was also his album with Magoo that went platinum. Sure, Vol. 2 was the biggest album that he worked on that time, but he was already established at that point.
The Neptunes- already had "Superthug" prior to Jay's "I Just Wanna Luv Ya". Mystikal's "Shake It Fast" was also huge around the time Jay girst started working with them.
A case could be made for him making Kanye and Just famous because their work on Blueprint definitely made them super producers.