What? No, what is the problem with people selling in-game currency. Why is that in any way negative.
You cited it as a bad thing that could result from people being able to exchange in-game currency.
Why do you see it as some terrible thing. The fact that it's against the game's rules doesn't mean it's a terrible thing automatically - rules can be changed or not enforced, after all.
Seriously, stopping people from exchanging currency is one of the dumbest things in this game. There is nothing bad that would come of allowing it.
Elite Dangerous is Frontier Developments Intelectual property, Gold sellers make money against the terms and conditions of that I.P, If frontier allowed this practice within their game they would be complicit in exposing their customers to Fraud and scams.
Gold selling is essentially a non official, against the T&C's potentially illigal form of Pay2Win. Frontier have officially stated that they will never introduce Pay2Win, Credit or ship purchasing mechanics for real world money as official game functions. Gold selling would be exactly that, except it would be black market and Frontier would see Zero capital from that trade as people make money from their property... So why should they allow it. They have not allowed it for 5 years now, and i don't expect them to start now.
The general consensus within this community (as this subject has popped up numberous times) is that people do not want mechanics that allow people to pay their way through Elite dangerous with a credit card. It seems that Frontier also agree, hense the statements made.
Its no surprise or secret that gamers generally don't like mechanics which allow players to use credit cards to pay their way through game content, Even with solo games its typically throwned upon. If you are the least able to understand why this attitude is generally prevailing in the gaming community then you can understand why is not popular here.
When i see a game that offers credit card short cuts to players, even unofficially like with gold selling... i personally tend to take my business elsewhere. Frontier have a large invested player base which has played this game loyally for almost half a decade. If Frontier wish to risk losing them (my self included), then this issue would be one way to accomplish that.