Thank you for raising the question! I just finished reading the Steemit whitepaper. Under the section "Shifting Toward Blockchain-based Attribution" on page 43 they discuss this matter briefly. (https://steem.io/SteemWhitePaper.pdf)
I myself decided to value the timestamping and proof of original work quite high. It's the reason I moved to Steemit in the first place!

Thanks also to the many good comments. Keep steeming :-)