D2R didn't pioneer them

Real-time money transactions aren't a novelty by any stretch of imagination. D2R didn't pioneer them, and it would be untrue to claim that they are a fact. Blizzard's action-RPG isn't the root source, but it is instead the most savage amalgamation of different free-to-play mobile and PC games. There are two Battle Passes, both with distinct rewards unique to a particular character (and not included in your general roster) and with too many various currencies for the average player to keep track of D2R Items economy reads as a massive mobile marketplace.

Even though they're sometimes met with resistance however, have become commonplace within the entire industry. You could argue that prevalence of loot boxes or other real-money transactions in AAA games has played a role in the development of this precarious economy. However, the more AAA gaming shifts towards the games-as a service model more, the more it has the same characteristics as game-based mobile apps that've been within this highly popular realm for almost a decade.

And this isn't just apparent in the use of money to purchase items and gacha mechanics and disclosure of drop rates among uncommon items. Gacha refers to making use of in-game currency, regardless of whether it's free, or purchased from an in-game shop to obtain something at random: pieces of equipment, for instance, in the case of Dissidia Final Fantasy Opera Omnia or characters from the ever popular (and ever-lasting) Fate/Grand Order or Genshin Impact.

In the case of D2R this is the method of using Legendary Crests (which can be bought or earned) to increase the odds of a five-star gem appearing in the dungeons of the endgame. While it's not completely traditional in its presentation (most gachas are played by "rolling" on a short-lived banner) Players are engaging in randomness in the same way. In many ways in many ways, Diablo is a classic Diablo franchise was building toward these Diablo 2 Resurrected Items mechanics since its beginning, as Maddy Myers wrote a few weeks back.