I agree this is a misconception but not for the same reasons. What would happen is that all different companies would end up implementing the same functionalit

I agree this is a misconception but not for the same reasons. What would happen is that all different companies would end up implementing the same functionalities over and over again. I know companies that don't rely on OSS for security reasons and that's exactly what happens. Maybe some companies would step up together and publish a shared There would be a tiny bit more of demands compared to nowadays, SWEs would find it harder to move companies - but I don't think SWEs productivity wouldn't be affected, once they finish onboarding and learning whatever the standard library in a specific company works like.