He can make 20 posts if he wants or he can make 200 posts if he wants but that doesn't change the fact that the referenced posts are unnecessary and spam. He seems to have a history of making several posts in a short burst followed by no posts for several weeks, this could indicate that he has several accounts and is trying to make the minimum number of posts for the campaign that each account is in (this in itself is no big deal provided that his posts contribute to the conversation, but they do not), or it could mean that he has one account that participates in a signature campaign and does not want to get removed from said campaign for inactivity (again no big deal as long as he doesn't post random crap, but again not the case). 

Are you talking about this guy? Or are you talking about how signature spammers are often telling people to accept escrow in random marketplace threads?

The overall point is that he is fairly clearly pulling up several threads in the same sub at once and posting almost the exact same thing in each thread very quickly. I think it is obvious that he is posting for his post count and is not contributing to any of the threads.

Some of the threads he posted in likely were locked by a moderator as they have served this purpose. Some threads attracted additional unnecessary posts from others sometimes saying to stop bumping so many threads some saying nearly similar unnecessary things (e.g. Paid posts that add nothing to the thread).