I think that point can support working for either a big company or a small company depending on what type of impact you are looking for.
I've worked for startups in the past and have had a huge impact on the startup but almost no impact on the outside world because the startups just weren't tackling very visible problems.
Now I work for Google and I have basically zero impact on Google i.e. basically nothing that I can do will ever move the dial in terms of Google's revenue, etc. But I've worked on several projects that have had a big impact outside of Google. For example, I was on a small team (3 people) that developed the Python 2.7 runtime for App Engine (this was a while ago) and I was on another small team that implemented the server-side infrastructure for the Google Home. I also developed the screensaver for Chromecast - which is a tiny tiny project - but still millions of people love it.