If anything, I would consider someone making that statement miss informed
That's not the best of reasons; just because Django is not used by Google doesn't mean it isn't the perfect tool for you.
Others: DigitalOcean, Pinterest (used Django at first, may have moved to Flask by now, not sure), Mozilla, Disqus, Robinhood, The Washington Post.
Update: Just saw that HN user txcwpalpha said the same about Disqus in sibling comment.