asdf version dependency

[Robert Goldman]

I think that your argument suffers from mixing together the concepts of
"version control" and "versioned software."  Version control is indeed
the concern of version control systems such as git and subversion.  But
versioned software is not, as witness the use of version management in
software installation systems such as RPM and apt.

Indeed, if everything is managed in a single, or a set of interconnected
VCSes, version control is less important, as you point out.  However,
when one is not using VCS, e.g., when using quicklisp, or assembling
software oneself from multiple locations, versioning (not version
control) is important to efficiently assemble a coherent set of subsystems.

Even when using VCS it can be helpful.  I work with people who
concurrently work on multiple different lisp-based projects.  Those
projects use different mixes of libraries, and at times even different
versions of the same library in different projects.  Sometimes,
inadvertently, ASDF settings can bleed through from one project to
another.  In such cases -- event when VCSes are pervasively used -- it
can be quite helpful to have version metadata.

Best,
r