The context is companies with 30+ engineers. At that point you're going to want some form of formal project methodology that allows everyone to co-exist somewhat peacefully. Generally, the results otherwise are varying level of dysfunctional.

I worked in a handful of teams at Google and none used Agile (I believe some do, but they're a minority), and very little formality besides a weekly team meeting. From what I hear, FB and other big companies are in a similar situation. Sure, you can stretch the definition and say they're dysfunctional ("omg lol google kills projects") but you can't deny they're successful.

First of all, I used the word Agile in my response zero times. I used the words formal project management for a reason. Agile tends to be assumed but if someone asks then either you can infer what they actually want or you're going to be a terrible hire in a startup anyway.

Second of all, as people love to say here, your small or medium sized company isn't Google so you shouldn't make decisions as if it was. What works for Google does not necessarily work for random startup or small company number 7521. Every small and medium company I've seen without a project management process was a disaster. Partially because, unlike Google, they can't throw 10 million at a problem and shrug if they waste 9 of it or cancel the whole thing in 2 months.