[stbullard]

The majority of Twitter's revenue comes from mobile ads, and app install ads are a major component of that major component. Knowing what apps you do or don't have installed allows them to better target app install ads, and I imagine that's the reason for collecting this data.

So, if you don't have Clash of Clans installed, they can show you a Clash of Clans ad. If do you have Clash of Clans installed, they can then prompt you to reengage with it, or suggest other apps you're likely to install on the basis of your having shown an interest in games.