I see no reason Elite couldn't have a more advanced economic BGS that took things like supply chains into account,
And who would deal with the supply chains?
For example, let's take Demand in ED. IMO it's a nice idea. For a single player game.
Personally i'm pretty miffed by the Demand set for certain commodities (read precious minerals and in some cases metals).
Most of the time it was so small that a single player can fill it up for a single station in less than one hour after the BGS tick .
And the Demand being small was one thing, then it was also set on a really slow recover rate.
If ED was a single player game, this would not be an issue.
It's not a issue for an obscure commodity that nobody trades.
But it was a big issue when thousand of players were mining LTD, but only a few of them managed to sell for good profits to the stations (that had the required combination of BGS states to be able to offer a big price) before the Demand was fulfilled and the price dropped dramatically
In a single player game a lot of things can be set in certain ways and they will always work.
In a multiplayer game, it really depends on the number of players hitting a certain market/commodity while the way BGS works it means it favors the players that can connect to the game when the tick is happening
Too little players, and certain trading settings have no effect. Too many and trading starts looking like a 1h window of opportunity