[x0x0]

one guess

   We will notify you about this feature being turned on for your account by 
   showing a prompt letting you know that to help tailor your experience, 
   Twitter uses the apps on your device. Until you see this prompt, this 
   setting is turned off and we are not collecting a list of your apps. If you 
   do not see Tailor Twitter based on my apps in your account settings, app 
   graph collection is not occurring for your account.

So it's opt-in with a default of off.

second, some partners are more equal than others...