Earlier quoted context omitted.
I think that the major difference is a lot of games/apps are tailor made to produce dopamine/cause addiction. While a good book _can_ be addicting, it's not inherently stimulating.
Why would a book not be made to produce dopamine? They're written by people trying to make the most engaging and profitable story possible
From the way some people talk about video games on here sometimes I assume they think the android/ios market is representative of all of gaming (even then there's plenty of good "buy once" mobile games without microtransactions, the discoverability on the stores is just godawful - presumably to steer people towards more profitable crap rather than what's actually good).