Besides the excellent reasons already posted here, I would also point out that many, perhaps most, Wall Street Journal articles posted here tend to be the same

Besides the excellent reasons already posted here, I would also point out that many, perhaps most, Wall Street Journal articles posted here tend to be the same story that other outlets are covering, often better, and usually the WSJ articles has nothing to recommend it over these other, free outlets. So by blocking WSJ submissions, it would encourage submitters to use an alternate source for the topic.