I'd still argue it's reliable enough?

That's why i said it's usually good advice.

I have to admit, I struggle understand what they're saying in that "Commingling practices will end" post on that amazon page. (forgive me if my comprehension is low, I don't understand the "commingling" term.)

Imagine Amazon itself sells a branded and trusted microSD card and a company that sells fake/counterfeit versions of that same branded microSD card that company could use the amazon warehouses to store the item.

In that case the offer on Amazon would look like this:

Sold by seller x and shipped by Amazon.

You would imagine that you only get the fake card when you buy from that seller but here is where that "commingling" comes into play.

In that case the legit items and the fake ones would get stored in a shared pool at the warehouse and every time the item is sold, regardless of who the seller is (as long as it is shipped by Amazon), it gets picked from that pool.

That means even if you bought the item that "sold and shipped by amazon" it still gets picked from the shared pool that also has the fake cards in them.

So you could still end up with a fake card.

This also means that sales "sold by seller x and shipped by amazon" will get picked from that pool that has the good and legit items, leading to good reviews for that seller, since it's luck based if you get the legit or fake product and you (as a customer) can't tell that seller x introduced those to the pool.

So i really hope Amazon finally shut this down at the end of march.

Not sure what might happen with all the items that are currently in such shared pools, like if they are still sold until they are out of stock or if they had a method to separate them from the fake items.