It's not in the mainstream because the investigative reporting was done by a Twitter user. The mainstream stories will come, give it time, needs to be more of a story than line items in financial filings.
From the MLB owners' perspective, I have no doubt that they let all of this happen to push the salary cap narrative. Surely people knew about the revenue sharing manipulation. Surely other teams are also trying to hide revenue or at least exploiting loopholes.
There will be repercussions.