Totally agree, the authors seem to be missing the point that these libraries are a new layer between the posix api's and the end result which is typically a GUI application. The fact these libraries also bring a walled garden to the table which bypass the posix api's also demonstrate how security is being bypassed.
Plus with the analysis only featuring the 3 os's Android, OS X and Ubuntu, they would have noticed that Windows OS's pretty much mirror what POSIX does as well.
1 "usage is driven by high-level frameworks, which impacts POSIX’s portability goals.", that's the libraries/frameworks fault, plus have they heard of GCC? It works on many OS's.
2 "extension APIs, namely ioctl, dominate modern POSIX usage patterns as OS developers
increasingly use them to build support for abstractions missing from the POSIX standard" Perhaps they have missed the point, that without the POSIX standard these extensions would not exist in the first place. They might just complain about procedural coding practices being outdated when comparing to OOP coding practices, even though OOP brings slow bloat to the table as well. Perhaps a better question to ask is, why has a framework/library got some functionality which could have used some of the POSIX api's but didn't? Was it expedient to keep it within the framework/library and bypass the Posix API's altogether?
3."new abstractions are arising, driven by the same POSIX limitations across the three OSes, but the new abstractions are not converging." So abstractions are a new name for libraries and framework and not the concept like OOP coding is an abstraction. Perhaps complaining to the authors of libraries and frameworks that don't port would be better?
POSIX is like a foundation that allows creativity to take place. This is why we see the differences in libs/frameworks, different OS's have different parameters, different design ethos or objectives. Even in Windows, some API's are used more frequently than others, for example I cant remember when I last used the API's involved in getting a dial up modem to work, or using API's to print direct to a dot matrix printer. This paper just seems to be an analysis of API's not used as frequently as they used to be, sometimes because libraries/frameworks have rightly or wrongly replaced them for a myriad of reasons.
Qudos to them for downloading so many apps and analysing them though. Just what you need if you are looking for backdoors en-masse or exploitable bugs.