The way this has come about with relation to web and internet software is that the actual applications being built are closed source but a lot of the libraries

The way this has come about with relation to web and internet software is that the actual applications being built are closed source but a lot of the libraries and commodity pieces of software are being open sourced with permissive licenses. for eg. Twitter, Google, Facebook etc. produces and consumer a lot of open source software but their core products are still close source. You can segment out portions of your software stack and release them for free while still retaining a competitive advantage with your core application. This isn't an all-or-nothing decision and this hybrid approach is the most common. I think Twitter is a good example. They both built and scaled up using open source and also contributed their own open source software, which has been improved upon by others and in-turn benefited Twitter. It didn't require a license where contribution was essential and nor did it require giving up any competitive advantage (i'd argue it solidified their position).