That's certainly an alternative possibility; more likely, IMHO, than sellers copying one-another perfectly. However...
> 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.
