I agree and this is why the solution is that steam should give players the funds to buy these loot boxes themselves; create a fictional currency (lots of these games do that anyway) and give players the power to just play the game for that currency, or better yet just give them that currency so they can buy them; you maintain the lootboxes and their random nature and players get to avoid spending real world money buying them. There's a lot of games today that already incorporate that mechanic where you can earn in-game currency to buy lootboxes. As for players then turning around and selling their accounts or items for real world money, the buyer is not getting a CHANCE at that item, he's buying something he knows he's getting for certain.

To avoid turning killing bosses in WoW into gambling, the game can make it so you can fight those bosses for free, and instead incorporate costs into the game via (again) a fictional currency that allows you to buy consummables to make the fight more manageable. This way the player avoids spending real world money on this boss, and then whatever he gets, he can sell as a concrete item that the buyer knows for certain he will get.