Can you adapt proprietary software to your custom needs?... no!
Can you verify the code of proprietary software?... no!
Can you integrate proprietary software in a hardened system (RBAC/MAC)?... no!
If proprietary closed source software is as good or better than open source software, why does it ALWAYS have more code for less functionality?... yeah right...
If the standard of comparison is the performance on hardware platforms for which there is no open source software possible because of lack of documentation, then it's easy to tell people that closed source software is as good as open source software... but that's why only dumb people buy hardware with bootlockers and only proprietary drivers right...
Open source always develops further than proprietary solutions, leading to better results. Look at Dalvik for instance, based upon the ideas of Oracle with JVM, which is being replaced with ART. Oracle just can't make that evolution, they can't make that step, because they don't want to open source completely, so once ART becomes mainstream (which is probably going to be very soon), Oracle will have a tough time convincing embedded Java integrators to stay with the Oracle solution and not look to open source solutions that will probably use less power and have more performance, and cost nothing in terms of licenses... hmmmm... so all the benefits for less cost... yeah, tough decision...
Closed source ends where open source starts, that will always be the case. Even the richest software manufacturers do not have enough money to afford the equivalent of open source development. Even Apple had to steal from open source to make OSX/iOS work, they just took OpenBSD because it has an Apache License and not a GPL license, otherwise they would have taken Linux. Lesson learned, BSD was pushed back, and all major innovative projects are Linux/GPL based. Even proprietary software that was stolen 1:1 from GPL open source software, like Intel's VxWorks, don't work as well as straight open source software, best example being the Curiosity Rover. IBM has statistics about reliability and performance on big data systems on its website, those statistics are more than indicative enough: open source software always wins by a large margin in terms of quality.
There is hardly a single presentation of a launch of a proprietary software product that doesn't at some point involve technical problems. Apple had that, Microsoft had plenty of that. These softwares crash in front of the audience at the presentation, which basically means within a few minutes. Has anyone ever seen that happen with open source software? No! Because it wouldn't be released until it's finished and of good quality. An open source alpha software is often better than a repeatedly service packed and years old closed source software. Example: Manjaro is still not at version 1.0 by a long shot, yet in it's alpha/beta stage, it's a thousand times better than Windows 7 with the latest service pack, and it's a whole lot more innovative and offers a whole lot more performance and features, and works on a whole lot more hardware, including with things like the Microsoft Fingerprint Reader, for which Microsoft broke compatibility with its own Windows operating system after Vista... if they can't even assure compatibility with their own products, what can they do? Oh right... lie to people about the security and privacy of their closed source software... lmao!
The license model has nothing to do with the copyright. By licensing software as GPL, a developer doesn't give away any copyrights. In fact, he couldn't give away the copyright of an open source software if he wanted to, because it's inalienable, whereas he wouldn't even acquire the copyright of a proprietary software made for a corporation. Open source protects developers, closed source is the death of developers. Software patents must just die as soon as possible, and software should all be open sourced for transparency reasons, because it's the only way to stop the huge fraud that is happening. That doesn't mean that software should all be free as in libre, or as in free beer. If a company has a hardware technology that is so advanced that others can't copy it, and registers a hardware patent so that others can't copy it for cheap, why would they not ask money to use the open source APIs for the hardware product. But if another company makes something better, that's where patents become stupid, because at that point, they block innovation and progress, and that's against the interest of humanity.