If you need to reference LoL/Fortnite to make a point, you are not making a point.
In fact, there are very few games that have done the f2p walk successfully, sustainably, and all of them pale in comparison to the few extraordinary exceptions.
There are a _ton_ of successful f2p games with reasonable monetization models - Valorant, CSGO, Warzone, Dota, Path of Exile, Lost Ark, Hearthstone, etc. It's just that games in general are a power law industry - I don't think monetization model is really what will prevent a game from being successful. In fact, much of the discourse around Immortal is that the gameplay itself is in fact top notch. Blizzard has the dedicated fanbase to make a healthy profit and more with a reasonable cash shop - they don't _need_ to resort to these extremely cash-grabby mechanics.
Cash grab will always be superior especially when you factor in the effort making the game. MMOs will be magnitudes harder than making mobile cash grab games.
I honestly thought it was inevitable for Blizzard to go down this route the moment I saw the revenue slides post acquisition. In that slide it showed that King’s mobile games made way more than Blizzards games. At that point, all the MBA suits in the board must have started thinking, “why go through all the hoops of making a good game when you could spend way less money and effort to milk the cash cows?”
Thus the pressure started mounting up on Blizzard to create more “efficient” games like Hearthstone and newer releases instead spending long time creating and refining a game like they have before.
Precisely this, I feel like the only middle-ground here is not to sell your company to corporate overlords, we learned that lesson with many other companies.
Simon Sinek has a really good point in his book "Start With Why" that basically says selling your company is a complete failure, because you basically lose your autonomy and ability to adapt to unique market conditions that let companies be successful in the first place.
If you sell your company, presumably you don't care about its future success anymore and now you have a bunch of money with which you can do whatever you want.
Lost Ark and Genshin manage to be both very cash grab and very reasonable as a free-2-play. You can spend a lot of money on both, and pay-2-win in both, but still get to experience the whole game at a reasonable pace as a f2p player.
Diablo Immortal seems to do many of the same things, but just in a much more egregious way. So far I've heard a lot about how much money you can spend on the game, but not much about how bad it makes the f2p player's experience.
In Lost Ark and Genshin most players don't care that much about whales spending 10k to deal 100% extra damage because it's purely player-vs-environment and that sort of damage boost is totally excessive and unnecessary.
But many games make progress feel extremely slow or otherwise aggravating to push purchases.
I haven't really heard much about where Diablo Immortal lies on that scale.
As an anecdote, in Genshin F2P is totally adequate — its key feature is that max character level is constrained and easily achievable, so the main difficulty becomes getting new rare characters, especially if you’re impatient.
Back when I was in the industry there was very few games that did better than breaking even. It's the same reason you don't see a lot of independent large studios any more. If you need to hit the top 15-20% to make it only publishers who can afford to spread out the risk are able to stay afloat.
In fact, there are very few games that have done the f2p walk successfully, sustainably, and all of them pale in comparison to the few extraordinary exceptions.