I wholeheartedly agree with the part of the plagiarism article that talks about how difficult it can be for non-native and native English speakers to come up with acceptable paraphrases. I believe this to be especially true for individuals that do not particularly enjoy writing. Often I find myself wondering if I have changed the sentence around enough that it can now be considered something new and it is usually at those times I opt to use quotes instead.
For writers that are using English as their L2, I surmise that the process could be all the more challenging. But I do think that it could be a way to help them develop or further their language skills. It could potentially force them to think more in English and that would boost their cognitive skills.