Its blessing and a curse. I think software would be better if coders read mans and other documentation more often (and standards like RFC where it is applicable).
> git - Revision control that is low enough overhead that you need to have a reason not to use it.
RCS - 1982 CVS - 1990
They are limited compare to git, but they perform the main function - track changes in text files allowing to see previous versions, a diff for each change, commit messages. CVS compare to tarballs for each release (or worse to a mess of files .bak, .bak2 e. t. c.) is a breakthrough. Subversion, Mercurial, git is IMHO just evolution of earlier VCS.
> Package managers - By making it easy to include other peoples code we lower the bar to doing so.
CPAN - 1993 FreeBSD pkg_add - 1993
> Open-source software as a commodity
Here I fully agree. Opensource started to get some traction 20ish years ago (probably thanks to more widely available Internet and support from corporations like IBM), but its use is still growing.
When I look back it seems to me that 1990s were very fruitful and the next 20 years progress in software was somewhat slower, but progress in hardware enabled previously impossible stuff without revolutionary changes in software.