Blurt was created with a fork from Steemit in early 2020 (similar to Hive). Anyone who had a Steemit account prior to the fork will also have a Blurt account. If you don't have an account, click here to join.
Blurt is organised differently from Steemit and Hive. There is no Blurtdollar, and there is no downvoting. Instead they control spam with transaction fees (which are paid out of liquid Blurt in your account).
What are the transactionfees?
On the right-hand column of the blurt blog they always show the current transaction fees. Here is a screen-shot from today:
As you can tell the longer your post, the bigger the transaction fee to publish. Most Blurt curators will not upvote if your post is less than 300 words. But other than that, the system encourages you to post concise articles rather than over long articles that no one reads.
Other transactions such as upvoting, claiming rewards, powering up or down and commenting also have transaction fees - you are always warned about fees before a transaction.
So as you can see, while you are free from downvotes, the fees make it hostile and unproductive for spammers.
In addition you are forced to think about the cost vs the benefits of every action you take.