I know this is far from new or original but the problem clearly still exists.
Right now, assuming that you had not played during the release time of the adventure, the only way to obtain these adventures is through the payment of approximately $20. However, if you had played during the release of the adventure, you can obtain each wing for 700 gold (in-game money).
The main basis behind not making these older adventures visible for newer players was the risk that newer players would spend money or time grinding something that can’t even be used in standard, the main game mode.
However, this argument has several major flaws. First, if the only problem was the chance of scamming newer players, then why is the adventure still obtainable through the payment of irl money? Secondly, why couldn’t it be made so that the locked version could be obtainable for free while you could pay irl money for a fully unlocked version if you wanted that?
The truth is that this wouldn’t even be much of a problem if the cards that could be obtained from the adventures had no use. HOWEVER, standard gets boring after a while and after standard gets boring, wild is the place to go. However, all cards released before I started before I played can only be obtained through dust or irl money, neither of which I have much of. Plus, the adventures are all described as well designed and fun to play… if only I could actually play them.