I hope someone experienced can explain to me is paraphrasing the text for his own sake ^{[perhap out of merit]} without linking the source is allowed and not against the rule of this forum?

Plagiarism is often quite obvious: if a bounty spammer suddenly created a long post, that's a red flag. Or if someone earned all his Merit only from one post.
Sometimes it's easy to detect, but when they use a word spinner it becomes much more difficult (and more satisfying to catch them).