In 2019 you're more or less correct, but only due to cost and time constraints. Short-form public messaging on the blockchain already exists[0], it's just prohibitively expensive and slow. Imagine a blockchain with cheap, fast transactions. This should be harder to censor than other distributed solutions like a federated network or a similar scheme hosted on IPFS since you're taking the whole chain with you in the event of censorship, whereas the other schemes allow just the hosts of particular data to be targeted. Even before the economics work for full-on blockchain twitter, we might see a cheaper blockchain/IPFS hybrid where at least some metadata is censorship resistant. Unless the government wins the war on information, I'm reasonably convinced that a better blockchain twitter is coming.

[0]: https://cryptograffiti.info