Earlier quoted context omitted.
i'm not necessarily familiar with all the services (or the specific dependencies) on that list, but a lot of it will be a knock on effect from e.g: fb login not working as expected People will very often see it as "service x with fb login is broken"
I work in one of these companies and I can confirm that is a network outage and even our internal tools hosted in our datacenter (so no dependencies with fb) are down
https://isc.sans.edu/forums/diary/CenturyLink+Outage+Causing...
https://www.zdnet.com/article/centurylink-outage-led-to-a-3-...