Yep, those two apps are contenders for trying to do as much in the background as possible that the OS will allow. They also are the biggest violators of Apple’s directive that any app running on iOS needs to be ready to die at any moment. It was originally because battery life was such an issue, so iOS maintained strict control of what could run.
As to why those two work so hard to “play dirty”? The phone owner is is Apple’s customer, but Facebook’s crop to be harvested.
