Good to go with adding such a feature in the btt forum. Plagiarism in our forum is only detected when somone report a copy pasted content but this can't totally reduce spam and plagiarism.
I used steemit forum since a good time where observ the work of a nice informative robot called
Cheetah which catch similar content published elswhere in the web after posting and he is allowed to comment the post with the original source of the content as it is allows to downvote users and even blacklist them.
This suggestion was proposed before and with the lack of admins to handle some loopholes, it's up for experienced developement users to create a solution.