More aim assist does not necessarily mean that the game becomes more accessible or better.
Elden Ring is a hard game, and difficult to master, and it has a massive audience.
You are comparing Apples and Oranges. Elden Ring is a challenging game but is mastering the base gameplay, the feeling of combat and moving around, which are the very basic things you do. Also, you're playing against AI most of the time, and those can be adapted to the settings. Go play Dark Souls 1 once again once you're done with Elden Ring and you will see how the basic gameplay can make such a difference for a very similar challenging game.
In Halo, if you don't feel the very basic of the gameplay, aka aiming, to be smooth, then the whole game falls apart, especially with the unpredictability of other players's behaviors. Also, aim assist is one element of the AIM system in Halo, and it was for once well explained in this video. The feeling is more that Infinite lack a good reticule magnetism during action than the bullet magnestism itself for example.
Halo has always been a very accessible shooter, thanks to its fair share of AIM assist and and generous Reticule magnetism, and that's one of the element that made it very popular on console. 343 offered a lesser aim and assistance for the aim since Halo 5, and now with Infinite, and the game became less accessible on part because of this.
The more AIM assist you put, the more accessible the game becomes. But, accessible and better are two different things. Too much AIM assist, and the game doesn't get better, it just feel like the game is aiming for you, but it now becomes very accessible for say.
There's a thin line to find between giving enough aim assistance so the game becomes accessible and feels good on controller, but not too much that you don't get satisfaction for your action. In my case, 343 didn't find this balance with most of the weapon in Infinite for a controller player.
