I'm a coin / blockchain developer as well, and having inability to delete or edit posts and usernames is stupidity. Because post contents are not written in the blockchain itself, it is written in another database that can be edited/deleted at any time, only the post identity number is written in the blockchain that can not be removed. Then each post ID is given a hash code to link the post to which block it was stored.

Why would you write a whole lot of contents in the blockchain when each block is limited in size? Why would you burden the blockchain network with billions of bytes to sync all nodes? When all you need is a Post ID number to send to all nodes in the network?

Steemit is so stubborn to not let us edit our post if we make mistakes in the post like wrong grammar or spelling or references. Writing something wrong or bad on steemit is terrible as it will be made available on the internet as in forever. 

Never use this platform to write a blog or something you are not sure to be still relevant in the future just to earn free Steem. If you want to own Steem, go and buy on the exchange. Don't ruin your credentials in the future for something you mistakenly wrote today!