"kept in a form which permits identification of data subjects for no longer than is necessary for the purposes for which the personal data are processed"

Keeping "account X purchased game Y" forever is necessary for the purpose of tracking ownership.

Based on how big companies typically behave, I assume that they are storing a metric buttload of other data on their users, which is not necessary for that purpose, and which they aren't inclined to separate out.

This is just like the cookie popup nonsense. You don't have to ask for permission to store necessary cookies. Cookie popups are ubiquitous because sites would rather bother every single visitor so that they can store unnecessary cookies.