Comment by hnfong

Exactly.

Facebook literally maintains a python fork: https://github.com/facebookincubator/cinder

Google invented "NoSQL" before anyone else knew what it was, and all those "cloud" tools they used internally were obviously proprietary (except the ones they open sourced). Ex-Googlers I work with typically had to spend quite a bit of time re-adjusting to the "inferior" tools and processes in other companies.

Microsoft invented their own development ecosystem, and the only reason it's "common" or "standard" in the tech community is because they sell it as a product. This is the same for Apple at least for iOS development, and Amazon for their cloud service offerings.

When companies have millions of dollars to spend on maintaining a custom development environment that they think will give them a competitive edge, they will do it. It's the smaller shops that can't afford not to go with the flow, so to speak.