Real-money transactions haven't Diablo 4 Gold been invented in any way by any stretch of the imagination. Diablo Immortal didn't pioneer them but it's untrue to claim that they are a the case. This action-RPG from Blizzard's isn't the sole of the problem, but rather the worst amalgamation of hundreds of free to play mobile and PC games.
With two different Battle Passes that each have unique rewards only available to characters (and not part of your overall roster) and too many different currencies for the average player to keep track of, Diablo Immortal's economy reads like a giant mobile market.
Even though they're sometimes faced with opposition they have been accepted as normal within the overall industry. One could argue that prevalence of loot boxes or other real-money transactions within AAA games has been a factor in this market that is a predatory one, but the more that AAA gaming moves towards the games-as-service model, the more it has in the same vein as mobile games that have existed within this very popular realm for nearly a decade.
This isn't just apparent in the use of pay currency to acquire items as well as gacha mechanics as well as in the information about drop rates in more difficult items. Gacha is the practice of using in-game currency, whether it was free or purchased by a shop in the game, to purchase something randomly: pieces of equipment, in the case Dissidia Final Fantasy Opera Omnia or characters from the ever popular (and long-running) Fate/Grand Order or Genshin Impact.
In the case of Diablo Immortal, this is the method of using Legendary Crests (which can be bought or earned) to increase the likelihood that a gem of 5 stars will appear in dungeons at the end of the game. Although it's not exactly traditional in its presentation (most gacha are performed through "rolling" in a time-limited banner) it is still engaging in randomness, in a similar fashion. In many ways this, the Diablo franchise has been building towards these sorts of buy Diablo IV Gold mechanics since the beginning of its existence, such as Maddy Myers wrote a few weeks ago.