About hours watched, did you somehow account for viewers like me who start a show, promptly fall asleep, and the episodes play all night.
Do you not awake to a prompt asking you to confirm that you are still actively watching?
No more nefarious or creepy than a screen saver.
I was quite annoyed when I saw it for the first time - I had music playing over my Bluetooth headset while cleaning my bathroom, so it was quite inconvenient to tap on the phone when YouTube suddenly paused it to check if I'm still there.
But if it's just for the ad-supported version, it makes sense.