Earlier quoted context omitted.
I assumed that this is a legal requirement for all big online stores - is that not the case?
No, it's a blatant cash-grab by all big online stores. And for awhile you can continue to search "shipped and sold by Company" but eventually that goes away, because the marketplace shit is pure profit for them. It sells out the brand and turns them all into eBay/Alibaba clones and it's a major danger sign. More and more I have to restrict Walmart to "stocked in store" to avoid useless crap.
The other development is having to check online reviews before purchasing just about anything. Previously, if I bought shelf brackets or similar, I could usually rely on the fact that they were stocked at at a reliable store to mean they were decent enough quality. They'd passed some sort of review. If they were terrible, they'd be pulled from shelves. But that's no longer the case. More and more cheap, unfit-for-purpose goods are being sold by formerly solid stores. They'll accept returns but keep stocking 1-star items and hoping most people forget to return. I've checked reviews and been saved by 1-2 star averages suggesting the manifold splits first use or the shelf supports a tenth of the rated weight.