Explanation for mysterious Chinese seeds raises even more questions

You've probably heard about the mysterious seeds shipped from China to addresses throughout the United States and Canada along with their Amazon orders. Rather than baby triffids, the seeds have actually been identified as, inter alia, mustard, cabbage, morning glory, mint, sage, rosemary, lavender, hibiscus and rose.
But even more mysterious than the seeds themselves is the reasoning behind it all. The best explanation (make that guess) as to why the seeds may have been sent is something called a "brushing scam", whereby a seller sends a buyer an unsolicited item so that they can then post a fake review in order to boost their profile and potentially increase sales.
The pretzel logic of this is so obscure that I have difficulty believing it is a real thing (and yet, there it is on Wikipedia). If they are going to post a fake review anyway, why bother mailing out anything at all? And why seeds (which are explicitly disallowed by the Universal Postal Union)? And can it really be financially worthwhile actually mailing some seeds halfway across the world in order to generate one good review (albeit a fake review for a fake order)?
It makes you realize just how screwed up the world of international commerce really is. It reminds me, in a way, of a Black Mirror episode called Nosedive, which paints an all-too-plausible picture of a society where people's entire socio-economic status is based on ratings or likes from every single social interaction they engage in.