"Addiction" is not caused by external stimuli/substances/objects/experiences, but is rather a symptom of underlying, internal suffering. The "addiction" is the escape from dread and immense suffering. We externalize "addiction" as a concept because it helps typical people (neurotypical, non-suffering, non-traumatized) to understand the phenomenon by shorthand (as we do with most symptoms of mental illness). We focus on how the externally visible behaviors impact typical people; on how inconvenient or unpleasant it is for us to handle these behaviors. Or we focus on specific cultural/social roles the "addict" is supposed to be filling, and on how the "addiction" impacts their ability to do so. This model of "addiction" does a huge disservice to us all.
The reason this particular game is prominently subject to "addiction" is that it has a more robust and complex effort/reward system than any other I'm aware of. The sheer variety and depth of content, and the love that was put into the original development, make for a wonderful respite from the horrors of embodied existence for many of us.
Just my two cents as an over-educated, super duper neurodivergent person who has been playing since release.