I sort of understand this..I have an app that, when it backs up the phone, instead of backing the phones contacts, backs every G-mail contact I have ever had, over 600 of them..90% one time contacts and 99% not on the device being backed up...
Very annoying.. I disabled that feature on the app.
Put another way, if I want to back up my phone, I ONLY want to backup the phone, not my entire Google history on all devices ever used or owned.