The distclean target in the release tarball removes files that are part of the tarball (and thus the released source). In other words, if I unpack a tarball and run make distclean, I lose e.g. configure, doc/tig.1, etc. This is especially problematic when trying to build a Debian package: the package builder will run make distclean first. It knows how to run autogen.sh to get configure back, but other files such as the manual pages are lost.

In my understanding, the distclean target should return the tree to the state of the distributed source code. If the distributed source contains a configure script and (generated) man pages, these should not be removed (I would suggest a pristine target for that).