Here's your bottom line up front: Amazon doesn't care about the quality of reviews. Period. Amazon cares about control of the process.
Here's how I know this:
I have been an amazon Vine member since 2009. At the time I was invited to start receiving "free" (no longer are they free: for the last two years, every item is assigned a "fair market value" (FMV) for tax purposes that results in an an annual 1099 for the IRS; generally the FMV is about 1/3 of the sticker price) items, I had written less than 20 reviews of things bought from amazon since 1997.
From 2012 until early last month, I also accepted and reviewed items provided directly to me through amazon vendors. Some where shipped directly to me, and some where provided through amazon via a vendor-supplied claim code that would result in an "amazon verified purchase badge. At the "high water mark" of my reviewing activity, I was ranked in the low two digits of amazon's "Top Reviewer Ranking" list.
The above represents three categories of reviews:
(1) Amazon supplied through Vine (which carries a giant green "Vine Customer Review of Free Product" banner)
(2) Vendor-supplied direct (and therefore, no "verified purchase" label)
(3) Vendor-supplied via claim code (and therefore labeled as "verified purchase"
(4) Things I bought from amazon with my own money (the "true" amazon verified purchases)
(5) Things I bought someplace else and reviewed on amazon.
For (1): Amazon generates the disclaimer.
For (2) and (3): I provided the disclaimer at the end of the review. I didn't make a rhetorical attempt to convince you that I had provided an "honest evaluation...blah blah blah.." .I simply stated that fact of receiving the item for reviewing, in order to comply with both Amazon and an FTC requirement.
I had no incentive to inflate the ratings on any of these products categories.
The stream of Vine items was not dependent on me offering a high rating, and I have 1-starred many big ticket items. Since 2009, the Vine program has sent me over 300 items..from Post-It notes and advance reviewer copies of books to high-end A/V equipment carrying 4-figure price tags; overall average value is about $65 for ALL products...but there is nearly a $1600 range between the most and least expensive items). I'll tell you more about why the scoring or strength of content was irrelevant to amazon in a second.
For vendor-provided items, the majority of these were Chinese-manufactured smalls (Bluetooth speakers, LED flashlights, Lightning cables, USB cables, kitchen items, RC vehicles, dashcams, GoPro knockoffs... although a few others popped into the "shiny" zone, and came from brand names you would recognize immediately), but I also had no incentive to inflate the scoring of these products either. Typically, the vendors had not read any of my reviews, they simply had my email address (and there is clearly an active network of vendors exchanging big lists of such email addresses). Before accepting an item I told each vendor that I would be disclosing the receipt of the item, and that the rating and review would be based directly on my user experience. The email associated with my amazon account received an average of about 35 such offers every day. Since amazon ended "incentived" reviews. I still get 15-20 offers daily, even though they are deleted without reading.
And for stuff I bought myself (on Amazon or elsewhere: just as with Vine and vendor-provided products: I reported my user experience. My overall average product rating was slightly above 4 for over 1600 reviews written since 2009..
In order, here's what amazon has done since October:
-Told ALL reviewers that they could no longer review items received for free from vendors.
-Deleted the entire contents of reviewers that amazon's magical systems decided were engaging in manipulative behavior. Sometimes this removed the reviews of obvious shill or dishonest reviewers...and sometimes this threw out the baby with the bathwater as honest reviewers lost their content (and reviewing "privileges") too.
-Limited the number of Vine reviews for products. In doing so, amazon quite randomly deleted the reviews of Vine members, including about 1/3 of mine. This culling of Vine product reviews was very random, and did not seem to consider date or the helpfulness of the reviews amazon removed. In my case, some of my disappeared Vine reviews were the "most helpful" for multiple categories of products (including a popular SOHO MFD, fiction and nonfiction books and software (office productivity and photo/video editing. Amazon removed exactly zero of my reviews of "incentivized" items.
-Limited the number of reviews of non-verified purchases to five per reviewer per week,
-There is NO indication that amazon has made a concerted effort to target and remove individual "icentivized" reviews, and I think the source article here is conflating the dumping of mostly bad reviewers with actual quality control on individual reviews that may have been incentivized.
Amazon values algorithm over content. Amazon also wants to be in control the flow of things going its customers at no cost that result in reviews. It makes money off the Vine program by charging those vendors to participate, but doesn't want the Vine reviews to dominate the product discussion.
So here's the effect on me. I used to take great pride in the quality of my reviews regardless of the source of the product or who paid for it. Many of my reviews (and especially Vine products included video content). I've complied with the no-vendor provided edict. I've also stopped reviewing items purchased from Amazon or elsewhere.
I'm only reviewing Vine items: a 100% review rate is a requirement for participation in the program. Since these have suddenly become subject to arbitrary deletion by Amazon, the amount of effort I invest in them is way down. Video/photos are no longer part of the mix, and my disclaimer about the new potential for amazon to delete the review is now longer than the review itself.
Amazon's playground, amazon's rules. Amazon's behavior towards reviewers shows an utter lack on interest in the quality of the content...so my reviews since the beginning of this month are now echoing that, as I hang around to score the free stuff that amazon still wants to send me.