Why are visual novels not considered games? Aren't they

the ones that are pure VNs are essentially choose your own adventure stories.
Since they have branching decisions, it's the absolute bare minimum of what you can call a game.

Now, I know there's some VNs that exist that don't have actual decision trees or multiple endings.
These are non-games, yet people still call them VNs.

>view several screens of character talking
>no choice you make actually alters the ending
>basically an interactive slideshow