I love that the OP brought up FreeSWITCH because this is one example where I believe it's most troubling for package maintainers, software engineers and system implementers alike. From a software engineer's perspective, including 3rd party libraries in one source tree it transfers the burden of maintenance and support to one project maintainer. Not reinventing the wheel is good and all, but you still have to maintain its integrity.

From a package maintainer's perspective, especially in the case of Debian, they must ensure that packages are stable and secure. It's their job to make sure security updates are released. In the case of FreeSWITCH, there's no distinction between the main source and its dependencies. Package maintainers might as well not bother with including software like FreeSWITCH in their repos or risk the integrity of their system.

System implementer's are mostly ambivalent about these issues until their distro's FreeSWITCH package includes broken dependencies or until their FreeSWITCH installation has a security exploit due to a library that can't be patched independently.

I love FreeSWITCH but I'm sorry to say that it's poorly architected. However, I'm a system implementer, so I don't care.