RANT_MODE: ON
Nothing new. This has been the case for years. The worst of it was that they used to (I think this might no longer be the case) accept reviews from anyone with an account, whether they bought the product or not.
We have direct experience on this. My wife used to sell products on Amazon. People were leaving reviews that tagged as "Verified Review" BEFORE the product was delivered. Often times they would buy an item, leave a review and cancel before it shipped.
Even worse, these products required some use before anyone could form an opinion. This did not matter at all. People could leave reviews before buying, right after buying, before receiving and when the package was dropped off, etc.
And, of course, 100% of the reviews left before the product shipped or before it arrived were negative. 100% of the review left by non-buyers were negative.
In other words, sellers on Amazon have been conducting armed warfare through negative reviews, star ratings and seller feedback.
The other thing they are doing is consuming competitor's advertising budget before prime time. Say you have a budget of $1000 per day for click-through-ads on Amazon. That's $30K per month. Competitors would hire people --usually in China or India-- to click on your ads furiously right after midnight US time. By the time people awoke in the US and went to buy on Amazon your $1,000 ad budget was gone and nobody saw your product offerings.
We burned through tens of thousands of dollars exactly this way. I had to fight Amazon for months to get them to have a look at the statistical analysis I put in front of them. At the end of that process they refunded us a fraction of our spend. What worse is that we lost all search ratings (some of our products were on page one for applicable keywords) and Amazon absolutely refused to turn back the clock and restore our standing. It was an absolute nightmare. They could not have cared less. This is when my wife decided to stop selling on Amazon. As a doctor she had no patience for that lunacy.
The other problem is that Amazon does not preserve advertising records (or they didn't back then). If you did not manually download your statistics with regularity there was no way you could reconstruct what happened six months ago. If I remember correctly you get a few weeks or one month's download and that's it. I don't know if it's true or not, but their seller-no-service people told me the records are not preserved.
Even worse, they refused to provide us with the identity of the seller or sellers who attacked our advertising budget and through negative reviews. They told me they identified them and banned them from Amazon. If they were in the US or Europe we wanted to seek legal action against them. Amazon, once again, could not have cared less.
Based on my experience and that of others whose lives have been turned upside-down by Amazon product and account suspensions as well as flat out fraud in reviews and ratings, I would not recommend that anyone bet their livelihood on Amazon. They could destroy your existence overnight. I know people who are still trying to recover from daring to think they could "build a business" on Amazon. It's a farce. You own nothing. They control everything. And they can flick you off the platform without consequence because you are less than a rounding error.
In our case we both benefited from having careers and a successful tech business, so the Amazon failure didn't hurt us badly. Not so for friends who, quite literally, depended on their "Amazon store" to live, thought they had a shot at improving their lives, risked money they could not afford to lose and actually wanted to own a nice lifestyle business.
RANT_MODE: OFF