After playing World of Warcraft for 15 years, I started becoming increasingly bored and disgruntled with the game. The game being grindy and repetitive is no real surprise, I mean it's an MMO. But the one thing that was really frustrating was paying monthly for a subscription and a huge chunk of cash for an expansion, but still having extra stuff flashed in my face all the time that was simply not possible to earn in-game. Mount skins, cosmetics, miscellaneous stuff that is only available in the Blizzard store. They also began adding loyalty items that require being subscribed every single month, and doing repetitive, extremely boring stuff on top of the other repetitive boring stuff, so basically double dipping on your grind, which really isn't fun.
Aside from that, I also played other games that required a heavy amount of grinding too, and each one of them had similarly frustrating elements. Destiny 2, overwatch, Battlefield, Fortnite, Halo, and the list goes on. Each of them has the same issue: fear of missing out. FOMO basically makes it so that if you don't seize the opportunity to spend real life money, you will never be able to obtain something really cool, because it's only there for a short time, and then it's gone, and you are made to feel guilty and bad about it. It's just kind of depressing playing kind of games and realizing that you are now mentally dependent on financial transactions in order to get the full enjoyment of the game. That to me is a very very awful way to live life, and it really messes with your emotions
So I ditched every game that had any element of an in-game purchase. This is honestly helped my mental health a huge, huge amount. Now, I only play games that either have no microtransactions in them at all, or are completely free and 100% possible to play with no purchase required at all. So games like team fortress, deadlocked, Stardew Valley, and many other indie games that you can purchase and then never have to worry about getting suckered into the microtransaction cycle for
So that's great, but halo IMO is the least FOMO inducing mp game on the market with battle passes. You can actually "equip" the season pass you want to level and work on it, the best thing is they never go away so there's literally not a single bit of FOMO, only the illusion. Regardless, I see your point for the other games and I commend you for making the change.