For the rest of us, it simply makes Diablo less enjoyable.
We've been there before or similar to it Diablo 4 Gold. When Diablo 3 was released in 2012, it featured an auction house in real money that players could buy and sell their items. In theory, this was to head off the fraud and cheating that plagued trading items on Diablo 2. But to get players to the auction house, Blizzard lowered loot drop rates in the game to such an such a degree that equipping your character became a thankless grind, and the game as a whole felt unrewarding to play. When the unpopular auction house was eliminated and drop rates was increased during 2014, Diablo 3 instantly became more enjoyable, even before changes of the Reaper of Souls expansion raised the game to a classic level.
The lesson: It may seem reasonable trying to make money off Diablo's loot, but the moment you start, you drain all the fun from the game. It's exactly the same with Diablo Immortal, and it is noticeable before you get to the endgame because it's embedded into the game design. The drops of loot are less important, while character progression is artificially throttled and thinly distributed across too many systems and are too sluggish and too granular. It's more carefully hidden than it was when Diablo 3 was launched. Diablo 3, but it's an equally boring slog. Buying a battle pass or spending huge amounts on legendary crests isn't much help since paying for an excellent item drop won't be as exciting as simply getting one.
I'm not sure if it is a way to isolate the core of what makes Diablo fun apart from the mechanics that make it a free-to-play commercialization. If there could be, Blizzard and NetEase have not found it. They've developed a mobile version of Diablo that's smooth as well as enjoyable and generous at first. But if you spend enough time with it there's no way to deny that the heart of the game has been ripped out to pieces, then chopped up and given back to you piecemeal buy Diablo IV Gold.