The first example of >>774
coming to mind was back before the last board went down, with an artist called DarkViperBara, who had switched to a monthly more expensive pack than his older low cost sparse pics posted, and suddenly there was a topic and his packs were being shared, not long after he started on his tumblr the "Free unlock" or "free Release" or something like that, in wich he posted some of the high quality images from the older packs in their actual 1080p size, if i'm not mistaken, so…
Artists know of this place and of many other image boards/forums where work gets shared. Some dont care, some request takedowns, some get angry and do smoething about it, like the crywolf series artist who decided to watermark his work with the patron's email in a sort of intrusive way to avoid sharing, because otherwise he'd know who shared and could take some action like blocking the person or something.
long story short, barachan dont have a DNP but artists are free to do their stuff whenever they want, how they react to their work being shared over the internet is up to them.