I don't believe GNU's triumph over the BSD derivates was for the most part technical, they just happened to be at the right moment at the right time to ride along Linux's success.
A consequence of the proliferation of arguments in the GNU tools is imho that it made the GNU manpages too verbose and information dense to the detriment of their usefulness.
That's exactly why RMS is so pissed at Linux being mentioned without GNU. The funny thing is that it is the license he shipped his code under that allowed them to do this, he could have made the license say 'if you use this code you are required to prefix the name of any project with 'GNU/'' and that would have been that. If you give people rights and freedom they will use them.
That is because of the "lawsuite", unless you are referring to the 80s.
Back then, Companies and Colleges were the ones who got UNIX. Companies went with AT&T, and IIRC Colleges when with BSD. So AT&T won out due to better financial backing and maybe a possible threat of AT&T going after BSD.
A consequence of the proliferation of arguments in the GNU tools is imho that it made the GNU manpages too verbose and information dense to the detriment of their usefulness.