I actually think it may be a design flaw to store everything permanently on the blockchain. Smarter would be to give access control rights to the owner of the power. This could be done through permissions of course and this would guarantee data ownership to the person who posted it. But of course the people who designed Steemit had a different opinion and are going with a similar design to IPFS which again may be flawed.
While I do not like censorship I also don't think everything should automatically be permanent. The person who controls the post should be able to remove access rights to it and while this isn't a delete it would be similar to revoking access keys. It could probably be done even on Steemit if Steemit chooses to integrate with Storj or something similar for the datastore or use a DHT instead of the blockchain but the blockchain was chosen.
This is not the first design which uses the blockchain either. There was Bitmessage which had an even better design than Steemit but Bitmessage was not accessible from the web which may have made all the difference. Also Bitmessage cannot scale either so even if the design was nice from a privacy perspective it could never scale.
RE: What to do if you want to delete a post?