system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If Ma Bell got broken apart for being a "regulated natural monopoly", why are cable companies allowed to function as monopolies?
gpt
They didn't get broken apart for being a natural monopoly, they got broken up for how they used their monopoly.  It's not against the Sherman act to have a monopoly, but many actions a monopolist attempts to leverage their monopoly advantages into other fields are against the law.