[d23]

For some companies where the barrier to entry is very high or requires a lot of market share to compete, this may be true. But for others where the investment in actually building the thing was the only barrier, giving the code out to the world can be a terrifying prospect.

[IgorPartola]

You are right, it's not always appropriate. However, in most cases, it's just fine. Here's a list of companies that I think could open up at least 95% of their code: Netflix, Hulu, Amazon, Tesla/Ford/GMC/Toyota/BMW/any car manufacturer, Apple, Home Depot/Walmart/Safeway/any retailer, Mint, Twitter, Facebook, Google, and many more.