YouTube wants to be able to cross reference people with Facebook and gmail, among other things. They want to be able to link people to a mobile phone number, from which they would have the ability to track 'persons of interest' through Google Earth.
I think YouTube hangs on to all of the uploaded videos blocked by copyright claim, so that eventually they can copyright those themselves, when the original copyright expires. They could also purge all videos that they don't want people to be able to see. I'm still experimenting with ways to try to post videos in forums that are on my own channel, but blocked from public view. I used to have a method that worked, but they made some programming changes to thwart it.
I recall one video critical of Feminism that required the viewer to sign in to their account, before it could be seen. Google and its affiliated sites want people to be permanently signed in to accounts, preferably with their real name, primarily through Facebook.
Most businesses have a five year business plan. Google's is 300 years, in which they would like to codify all knowledge from the entire history of Mankind. That might sound like a good idea, but not if you're someone living 300 years from now, and you have to pay Google to read, watch or listen to anything, and your choices are restricted to Google's approved list for the masses.
Google wants to rule the world, just not immediately.