Nothing prevents you from doing so. The power to persuade others to comply with your wishes is gained on Hive by accumulating tokens. That is the sole power HW has.
In truth no one has the power to ban anyone on the blockchain except 17 or more of the top 20 witnesses, who can fork the chain to remove anyone or anything they want, because code is infinitely mutable.
Communities and front ends like Peakd or Hive.Blog can mute accounts, but not ban them. I do not think that muting extends to their votes, and even muted accounts can up or down vote posts and comments across the blockchain. If that isn't true, I would appreciate being apprised of what is factually correct. Having witnessed a variety of flag wars since May 2017, I have witnessed muted accounts doing that, and believe it is still how the blockchain operates.
I am not here for very long but I think muting posts just makes them invisible. I understand that you can keep using HIVE even if all your new posts get down-voted to 0, but I think for most people that would also be enough to give up on HIVE. That's why I suggested that communities (not front ends) maybe should have some better tools to shield their members from hostile whale accounts. That is a complicated issue, and without a doubt changes like this could introduce some new possibilities for abuse, so I'd be curious to learn some other solutions that other people may have.
My point was that absent some extremely complex (I suspect) code that dramatically alters how the blockchain itself functions, communities that are users of the blockchain aren't availed any ability to restrict how the fundamental aspects of the blockchain work. Transactions are intrinsic to interoperability of users on the blockchain, and communities are abstractions that were added much later, overlain on the blockchain, not fundamental operations, such as transactions like votes.
Yes, solution for this problem likely wont be a trivial one. I don't think I'd have much to add at this point, but I am curious how will the situation develop.