Why we need Decentralised / open source Social media?

Facebook is great. But it becoming very dangerous. It can influence billions of people for their own greedy. It makes money by selling our private data. In the age of facebook, its easy for corporate and government to influence and change peoples opinion. We unknowingly gave too much power to facebook. Its not good. Like we separated the state from church in many countries. Its very much important and urgent to separate the corporate and government from people. But still the community power is massive than facebook. Steem is good initiative but still long way to go.