While I agree with the spirit of your comment, this is a very sweeping generalization. Many kinds of financial information are being shared regularly with the public and for publicly traded companies they're required by law. Many companies build their infrastructure on open source software, with proprietary glue being a small percent.
Knowing what you can or even should share (for marketing purposes) is crucial. Especially knowing that keeping information asymmetry forever is impossible.
This too is a sweeping generalization ;), a good one though. We're pretty fortunate to have a lot of our building blocks made using open source software. Boost libraries to openssl, most of the stack is open source including the programming language. Although, the proprietary glue is the important bit.
An architect's work is more than just bricks and mortar.