"A typical strategy for mobile games and any game using microtransactions, is to make the currency," an anonymous employee in the mobile game industry has told me. "Like the case, if D2R Items I were to spend $1, it could result in two different currencies (gold and jewels for instance). It's helpful to disguise the actual cash value spent since there isn't a one-to-one conversion. Additionally, we place less favorable deals in front of other ones to make the other deals look more lucrative and the players believe that they are smarter by saving from the other deals."
"In the company I worked in, there were weekly events with unique prizes and they were designed to allow you to [...] complete it with uncommon in-game currency, which would allow you to take home one of the prizes. But the designers also had offer additional milestone prizes in addition to that principal prize, which will normally require cash to get ahead in the competition. Many of our milestones and metrics to measure whether an event was successful is obviously how much people spent. We also measured sentiment, however, I believe the top-level executives have always been more interested in whether the event made people spend."
Real-time money transactions aren't a novelty by any stretch or imagination. Diablo 2 Resurrected didn't pioneer them and it's disingenuous to present that as truth. Blizzard's action-RPG isn't the root of the problem, but instead is the worst amalgamation of hundreds of free-to-play mobile and PC games. It comes with two distinct Battle Passes, each of which comes with different rewards, each exclusive to a character (and not to your entire roster) as well as too many different currencies for the average player to keep track of Diablo 2 Resurrected's market reads like a huge mobile marketplace.
The practices, even if they're faced with opposition but have now become commonplace in the gaming industry in general. One could argue that prevalence of loot boxes or other real-money transactions within AAA games have been a factor in this predatory economy -- but the more that AAA gaming shifts towards a models of games-as services is the more it has similarities with smartphones that've been within this highly popular realm for nearly a decade.
And this isn't just reflected in the use paid currency to purchase items however, it is also evident in gacha mechanics as well as in the public disclosure of drop rates for the more scarce items. Gacha is the practice of using in-game currency, whether it's free or acquired via an in-game store, to D2R Ladder Items buy acquire something random objects, in the case of Dissidia Final Fantasy Opera Omnia or characters from the ever popular (and persistant) Fate/Grand Order or Genshin Impact.