This says something about the future of Time Machine. While connecting a hard drive to a backup Mac directly will still work, Time Machine's convenience is that it works over the air. Whenever you're on your network, your Mac will back up.
There's been somewhat of a transition with iCloud Drive. Introducing versioning in macOS is another hint. Ultimately, users will be able to have their files backed up in iCloud with versions and deleted files accessible through a UI similar to what we know now as Time Machine.
I would hope the general public, given recent data breaches and legal issues, would be wary of turning over the keys to their entire digital life to a cloud provider like that. But then again, Google is top of the game so I think I am answering my own question.