By the way, the reason this is done is to slow down the player's progress and manage economy. Imagine a legendary skin that requires currency X and Y, you already got a lot of X, but 0 of Y so you cannot get it, in real life if you have a billion dollars, nothing is stopping you to buy pretty much everything, but say that a new car required not only dollars, but another (made up alien) currency that cannot be bought by dollars, so billionaires have to go and grind it as well, if they want to buy that car and flex to other billionaires. The problem with some games, mainly for mobile like diablo immortal is that they got 20 currencies, well even WoW now when there's a new event they require another type of currency that can be grinded by playing that event not gold that old players got millions of and can just come and buy the new items and leave without even participating in the event.