In the following article I will focus more on the use of blockchain to generally improve the surroundings of voting procedures. I am not going to dwell on voting system on the top of a blockchain(like a private Ethereum or Zcash).

We heard the accuses on Facebook during USA elections

See this for instance. Could something like that happen on a decentralised version of Facebook?

The main strength is the difficulty of censorship

If you compare with Facebook for example, you can assume user will only read what they want to see in their feed bubble. This won't be solved by the blockchain. Censorship on the other hand become a pain in the a$$: censoring require active attacks on the blockchain. Even better it is very hard to hide those attacks, hence users will know what is going on.
Users don't usely have this ability.

Is Steemit THE ONE?

Not yet, not right now and from the roadmap and the not-scheduled-anymore hardfork not any time soon.
Briefly, it is because:

• An attack on the witnesses is not so expensive (compared to say Ethereum)
• average users don't know how to access/interact with the blockchain without steemit.com/busy.org
• thus flagging someone effectively (and automatically as we have seen) silence a user