Your Opinion is Valid, and so is mine.For me this is simple.
Difficulty slider is valid only in full offline mode. furhther discussion is pointless as long as even solo player will have influence on BGS and markets.
No offline mode? So no difficulty level, swallow it, all of us bought this game with knowledge, that this isn't offline game, with knowledge, that progression is a thing, and with knowledge, that editing save is impossible. This game never was as easy as now, even without mining exploits.
And no, fact, that we can't achieve all stuff by doing only 1 thing is great.
However I think being able to choose how you achieve all stuff, would be better, if you had more than one way to do it.
By allowing all Items to be bought or sold, would allow players to choose what way they enjoy to do it.
Choice is always better than having none.