Companies this size will often hire consulting firms to "restructure" so they can blame the outside firm for choosing who to lay off which means it's a softer blow in terms of morale for the remaining employees.
If Zuckerberg said let's lay these people off, remaining employees might hold a resentment towards him. Conversely, if Accenture says it, then they don't.
Regardless, choosing people randomly using an algorithm? Wow.