Although they are sometimes opposed but have now become commonplace in the game industry as a whole. One could argue that the D2R Items widespread use of loot containers or other real-money transactions within AAA games have contributed to this kind of market that is a predatory one, but the more AAA gaming shifts towards the models of games-as services, the more it has to do with the mobile gaming that has existed within this extremely popular sphere for nearly a decade.
And this isn't just apparent in the use of paid currency to purchase items as well as gacha mechanics and disclosure of drop rates among the more scarce items. Gacha refers to using in-game currency whether it's free or purchased by a shop in the game, in order to get something you want: pieces of equipment, in the case of Dissidia Final Fantasy Opera Omnia, or characters in the ever-popular (and persistent) Fate/Grand Order or Genshin Impact.
In the case of D2R you can use the Legendary Crests (which can be bought or earned) to increase the odds of a 5-star gem appearing in dungeons that end the game. While it's not exactly traditional in its approach to presentation (most gacha are performed through "rolling" on a time-limited banner) the players are engaging in randomness in the same way. In many ways this is how it's like the Diablo franchise was working towards these kinds of mechanics since the beginning of its existence, according to a piece Maddy Myers wrote a few weeks back.
D2R also, in clear terms, draws directly from a "feeding" technique that a lot of Japanese, Korean, and Chinese mobile games have adapted for more than 10 years. "Feeding" means increasing the stats, attributes or rarity of a particular item by making duplicates of a drop. The duplicates are then fed to an item of the D2R Items buy same rarity in order to increase the overall stats of an item. Generally five copies are needed as the industry norm to max out a character or item.