Indeed, Hive is one of the most decentralized blockchains in terms of HIVE ownership. And it is better protected against similar attacks thanks to the additional 30 days cooling period for witness voting.
But other attack vectors remain, which may not be as critical, but still may cause a lot of pain.
For example, an account with sufficient HP can establish censorship on Hive by downvoting posts that express certain opinions. This can be very damaging to the onboarding of new users on Hive. Sure, we can fight back using upvotes, but a protracted battle can wear out the community.
Community should be able fight this and similar attacks using a “reset button”: switching to a new token, air dropped to all the members excluding abusers. And this would not require a launch of a new blockchain. It makes attacks not just expensive, but useless.
Another major problem: increased government regulations, which may complicate convertibility of tokens. Base-layer DeFi can be offer considerable protection to projects and communities.
I really don't think censorship via downvote is even a thing. I've been at the receiving end of a whale downvotes before, just because I upvoted someone they didn't like, and I still don't agree it's censorship. Everything is still on the chain.