" you can't have one company having that much power with regards to elections and public opinion."
Except, traditionally, we generally do. William Randolph Hurst's newspaper empire was so powerful that he could make nations go to war with one another. Rupert Murdoch owns so much of the British press that his support has been required to win an election here for the last 25 years (and through Fox News, he has largely controlled the Republican nomination process in the USA from 2000-2015).
I do think FB is headed for regulation sooner rather than later, though.