Conversation so far:
what are problems inherent in conglomerate ownership of mass communication
Stories can end up being biased or omitted so as not to offend advertisers or owners.
what companies dominate mass communications
As of 2020, the largest media conglomerates in terms of revenue rank Comcast, The Walt Disney Company, AT&T and ViacomCBS per Forbes.

Question: how did the conglomerates become so dominant
Self-contained rewrite: how did the media conglomerates become so dominant in mass communication