In addition, if your account has some STEEM Power, you should help out in downvoting/flagging these spam comments -- that account has gone from reputation 34 to 5, and if we can get it to 0 then its comments will appear less visibly, at the end of the list.
When you click the flag in the upper-right corner of a comment, it says:
Flagging a post can remove rewards and make this material less visible. Some common reasons to flag
Disagreement on rewards
Fraud or Plagiarism
Hate Speech or Internet Trolling
Intentional miss-categorized content or Spam
The posts this account is writing are #2, fraud and plagiarism (exact copies of @haejin's posts) -- and also #1, trying to earn rewards using someone else's content.
The comments that this account is spamming all over @haejin's blogs are both #3 and #4, trolling and hate speech, as well as content inappropriate for this blog, and spam.
It would be appropriate to comment once per post.
This is abuse, which that account has been doing outside of Steemit as well:
https://steemit.com/flamewar/@nijeah/someone-put-up-a-website-to-harass-lovely-berniesanders
A limit should indeed be applied to the number of comments in a post, a cooldown timer, or a catcha for user below a fixed reputation score.
looking at his comment history, I can't imagine the space that have been allocated on the blockchain for this shit.