Diablo Immortal has been given an extremely rough ride this business model -- perhaps disproportionately given that popular free-to-play competitors such as Genshin Impact and Diablo 4 Gold Lost Ark do not lack similar gacha mechanics that entice big-spending "whale" customers. Diablo's popularity and reputation among the core PC gaming audience, earned over a quarter of a century, is definitely a factor. It's also the case that Diablo's system is particularly challenging and the very nature of Diablo games has some connection to that.
When you buy legendary crests, remember that you're not buying a roll of the dice like the case with a FIFA Ultimate Team card pack like. You are buying a chance to fill the dice with dice, to get into the game engine to alter the drop rates (slightly) in your favor. Gaming mechanics are addicting and are not isolated from the addictive gameplay mechanics, but instead are tied directly to combat and loot drops that are part of the game. Diablo is scarily well-positioned to do this; as my colleague Maddy Myers pointed out, these games that focus on loot have always been characterized as slot machines, which Diablo Immortal's model of business makes real.
Blizzard has taken pains to stress that the monetization of Immortal can be ignored till the end of the game and it's true and it claims that the vast majority of players love the game without spending a dime, which is reasonable. However, it's untrue to say that the most enjoyable part of Diablo games lies in experiencing the story rather than maximizing the power of your character. It's just as untrue to claim that the games have always been designed to create desire to reach the power level of the players. For those who have a tendency towards gambling addiction, towards the addictive nature of Diablo's item gameand, perhaps, both -- the crest system, as it is known, can be exploitative and potentially very damaging.
For those who don't it just makes Diablo less fun.
We've been there before or somewhere similar. When Diablo 3 came out in 2012, it featured an auction house using real money, where players could purchase and sell their drops. The theory behind it was to head off the cheating and scamming that beset players on Diablo 2. But to steer players towards this auction-house, Blizzard lowered loot drop rates in Diablo 3 to such an degree that acquiring a character became a thankless grind and the game as in general was boring to play. After the unpopular auction house was eliminated and buy cheap Diablo IV Gold drop rates were raised in 2014, Diablo 3 instantly became more enjoyable, even before the developments of The Reaper of Souls expansion elevated the game to legendary status.