Dark marketplaces are these days really known for their scammers, I do not think its good for the bitcoin and we should not give it hope or boost their reputations..
These marketplaces are bad for the bitcoin because it gave the bitcoin a bad name.
While the dark marketplaces are bad in terms of creating a bad reputation for bitcoin, anything that causes money or currency to change hands (a transaction) is in fact good for that money since trade is happening and that is the purpose of any coin to facilitate trade.