In Diablo Immortal's case, there's the usage of legendary crests (which can be earned or purchased) to increase the odds of a five-star gem appearing in the dungeons at the end of the D2R Items game. While not entirely traditional in its approach to presentation (most gachas are played by "rolling" on a limited-time banner), players are still playing randomness that they are used to in other games in the same manner. In many ways this is how it's like the Diablo game has been working towards these sorts of mechanics since its beginnings, such as Maddy Myers wrote a few weeks back.
Diablo Immortal also, in the simplest terms, takes direct inspiration from a "feeding" mechanism that Japanese, Korean, and Chinese mobile games have used for over a decade. "Feeding" involves increasing the attributes, stats or the rarity of an item by getting a duplicate of a drop. These duplicates then are fed to an item with similar rarity to boost the overall stats of said item. Generally five copies are needed according to industry standards to max out a character or item.
My first exposure to "feeding" was in Fate/Grand Order, which was first launched on Japan in July 2015 and brought in a total of $4 billion dollars globally in 2019. To create a character that was the best that it can be I had to purchase duplicates of each. Then, when a particular campaign came around I paid upward of 300 euros for the character I'd wanted for years. However, I was unable to obtain the exact copies I required to fully appreciate this character's full potential. The rates for the highest-rated 5-star characters averaged at around 1.1%, it's no surprise that I was unable to obtain a duplicate of the character when I was enjoying the game (which I've since uninstalled). As of July 2021, Fate/Grand Order was the seventh highest-rated mobile game of all time, sitting just behind Konami's Puzzle and Dragons, which may be of interest, since it is also a gacha-based game.
In the GDC 2021 speech, Genshin Impact developer Hoyoverse (previously Mihoyo) outright admitted that the method used to create characters was focused on generating maximum amount of capital from its viewers. For example, the Raiden Shogun and Kokomi characters reruns that took place in March 2022 alone brought the company more than $33 million in revenues.
The moment was immortalized in videos and mockery, most that was due to failed audience expectations: Fans attending BlizzCon 2018 had been hoping for "Diablo 2 Resurrected" announcements. But it also came from buy D2R Ladder Items the stigma that still surrounds smartphones and games played in the West which is where the adoption of smartphones as a gaming platform has been slower than in the majority around the globe.
