The penalties are not only financial, but also restrict draft choices and IFA money for periods of time. It if were a fictitious cap, it wouldn't work as well as it does, even for franchises such as the Dodgers and Yankees, who have almost twice the revenue as the Cubs.
Here’s a specific example of penalties.
Cubs will have the #16 overall draft pick next year.
According to Roster Resource, Cubs spent about $34 M over the lowest CBT threshold. Had Cubs spent $6 additional and been $40 over the threshold, that #16 pick would instead become the #26 pick—-moving back 10 spots in the draft.