You'd expect, if you allowed someone to study your notes before a test, that they'd possibly end up using similar turns-of-phrase to yours on the test. You wouldn't expect that they'd end up learning to perfectly duplicate your handwriting. It'd both be too hard, and not worth it, to do so; and they already have their own handwriting style. So why would they?
And I think that might be going on here. Take a look at a Chinese-language web site, like http://news.baidu.com
You'll see that it has the "niche" punctuation you mentioned, lots of point form descriptions with emoji bullets, and nearly all the latin script on the page is composed of short strings of all-caps text (many of which are acronyms like "IPO" or "AEX" that would be nonsensical if you didn't already know what they meant).
Some of these stylistic elements are naturally going to bleed over into Amazon listings too.
> You'll see that it has the "niche" punctuation you mentioned
It does, but there are only two examples of it on the page right now. (It is a thing common to Chinese text generally, but it's not the first thing you'd reach for.)【】gets used on this page as a sort of "tag" or "section" for a story. In Amazon product descriptions, meanwhile, it's being used to form a sort of two-tier "【title】body" text; as if compressing a slide-deck slide onto a single line. That's not what those characters are "for", in Chinese. It's a misuse. A Chinese reader would be confused.
> lots of point form descriptions with emoji bullets,
There are no emoji bullets on Baidu; there are styled bullets. But also, when I say "emoji bullets", I don't mean that they use emoji as bullets; I mean that they use regular bullets, and then use emojis as additional "decorations" for each point. Like this: https://i.imgur.com/xW3uPEP.png . AFAIK, nobody does this, anywhere on the Internet, Chinese or otherwise, other than on these brands' Amazon product pages. Because it's silly.
Consider also: if this was just "the way Chinese people write product descriptions on marketplace websites", then you'd expect to see it happening on e.g. AliExpress, or among Chinese sellers on Wish.com. But you don't. On both of those sites, product listings (from Chinese sellers) just use regular, random+inconsistent styling, with a diffusion of different stylistic techniques spreading via natural selection of sellers; with none of these particular techniques being among them. It's only a certain implicit web of a few thousand Amazon product brands, that have this extremely-consistent style.
Consider a foreign seller who perhaps doesn't have a great grasp of the English language or the cultural context of the US. When you add your own spin to someone else's idea you are leveraging a lot of implicit knowledge to be able to spin it in a way that makes sense. If you don't have that implicit knowledge (and are not going to be penalized for verbatim copying) why try something different from what you have seen be successful already?
Or, to put that another way: if this were a "marketplace of ideas", there'd be a certain amount of mutation, of copying error, to be expected, from individual sellers not noticing all of the stylistic quirks other sellers use; and instead substituting something random.
But instead, what you see is perfect copying of style, with no mutation or variation, among what are ostensibly thousands of distinct sellers/brands. That's implausible.
(Also, for a bit of a knock-down argument I maybe should have pulled out sooner: when there's an update to the "optimal style" used by these brands? They all change. All at once. Thousands of different brands got rid of the 【】 — replacing it with [] — on the same day, some time last year. Real independent sellers, even if they notice tiny changes in popular style like that, can't react that fast, and don't have time to be constantly updating all their product listings. But a SaaS sales platform with a post-maintenance bot sure does!)
