A bit further down in the replies reustle mentions: `It's a shame /etc/hosts doesn't support wildcards`

I find that ridiculous. Is there a reason why it's that way?

It's been around since the beginning of time itself I guess. You can try something like dnsmasq. One liner in the conf file: address=/.facebook.com/127.0.0.1

edit: For Ubuntu this should work (one versions from Trusty and newer):

sudo touch /etc/NetworkManager/dnsmasq.d/local

Put these lines into the above file and save:

  address=/.facebook.com/127.0.0.1
  address=/.fbcdn.net/127.0.0.1
  address=/.tfbnw.net/127.0.0.1
  address=/.whatsapp.com/127.0.0.1
  address=/.instagram.com/127.0.0.1
  address=/.fb.com/127.0.0.1
  address=/.edgesuite.net/127.0.0.1
  address=/.metrix.net/127.0.0.1
  address=/.fbsbx.com/127.0.0.1
  address=/.fbcdn.com/127.0.0.1
  address=/.facebook.net/127.0.0.1
  address=/.edgekey.net/127.0.0.1
  address=/.cdninstagram.com/127.0.0.1
  address=/.akamaihd.net/127.0.0.1
  address=/.fb.me/127.0.0.1
  address=/.appspot.com/127.0.0.1

And then: sudo systemctl restart network-manager

My thoughts were also, why so many subdomains? I wonder if it is to make the list seem more impressive and Facebook more all-encompassing.

"If you want to block facebook you need to block almost a thousand websites!"

"Then we will browse in the shade."

Where/How did you get that list?

grep -Po '\w+\.\w+$' | sort | uniq -c | sort -rhk1

Bit sloppy because it doesn't pick up the domain names with dashes. But my point was that if you want to blacklist *.facebook.com you shouldn't try to enumerate every single variant of it, that's not durable.