They also recently admitted to loading other players entire profile including their stash, and other content that they “have” which you would have zero access to, into memory on your PC, anytime that user loads into your zone.
It’s why you can’t have more than four stash tabs, because other people’s computers would be negatively affected.
My developer friend tersely summarized this as “lazy programming”. To put it as briefly as I can, in his view, it’s likely that all of your stuff including inventory and stash are all part of your character object/class/whatever, so to load other players, your client has to load that character object, complete with everything they’re carrying and everything that they have in their stash.
IMO, this means you can mod the game to dump a list of everything another player is carrying/holding in their stash.
Seems like they have minimal, if any, separation between clients, other clients, and by proxy, their servers. So rules need to be enforced at the client level, so the other users and the servers can stay protected.