1. Clue and Flex still have day jobs and never walked away from that (and they had other shyt. Clue was a VJ and label owner, Flex had his car business). It's the same reason why DJ Envy abandoned putting out mixtapes himself and locked into The Breakfast Club.
2. Khaled being a producer was always in the studio.
3. Clue got swallowed up in the Roc-A-Fella breakup which is why he was done after The Professional Pt. 3
4. Someone else said it. DJ Khaled was tapped into a scene that Clue, Flex, Kay Slay, etc. didn't have. Add to it all the Down South connects he had as well as being part of TS, he could drop tapes forever, and he has.
Snapchat and that leap into social media saved him more than anything because even he was drying up after that YMCMB run. Once he became a human meme, it gave him a second wind that he's running with. Clue and Flex felt like DJ's from an older time period and in Flex's case, his fukkery is tied to his show.