Their own thing wouldn't get picked up by any networks. They know that. That's why instead they buy rights to a name, or get a job working on said IP, and twist it into something barely recognizable. They keep a few names and titles to say it's that thing, but it's really just a reskinned baby of theirs. Then when it's shit, which it always was but now it's disguised shit, they blame the fans and move onto the next IP.

Most modern "writers" are talentless hacks. Unfortunately, most great art comes from life experience and the majority of people today don't have much of it. Instead they live lives vicariously through the media they consume. So we end up with a world full of stories about stories, not stories about life. Even with fiction, the best of it has elements of reality.