See Ubisoft and selling EXP boosts so you don't have to grind as much in Assassin's Creed. They decided to make it a grind to encourage you to buy the "solution".
Aside from offering the ability to collect IAP in general I’m not sure what the case against Apple is here. Did they do something specific to incentivize the creation of these kinds of games?
Not really, mostly "the market" happened. For productive applications one could argue that the lack of upgrade pricing and trials has fueled the race to the bottom but this was never really a thing with games (as one could easily have a free demo and a paid full game on the store).
