Some of the biggest web services are written with Python. There are tradeoffs, just like everything else. I happen to work for a company with a gigantic python codebase. It would be a hell of a lot easier to refactor our systems if we were in a statically typed system, but we work around this by having shitloads of tests. Tradeoffs.

I don't think python is good for large systems, but for companies, it's hard to get to that point without something that you can prototype quickly with.