What I learned from this post:

* The author thinks startups are better than large companies

* The author thinks senior developers at large companies are older than startup developers --- else, why bring up age?

* Despite admonishing his protagonist to learn one new language per year, the author believes "career rust" is a problem of age --- else the story would have worked with a 28 year old dev still writing in PHP.

* The author really likes unit tests.