Which is fine as long as you rely on the hash of the tag rather than the hash of the tarball.
> despite the fact that they won’t contain preprocessed autoconf
This is a feature; run `autoreconf -vfi` at build time, so that you don't depend on the maintainer's idiosyncratic autotools setup and local macros, and so that you can reliably regenerate it all if you want to change configure.ac or Makefile.am.
On a package bulk build machine, that’s a lot (like, a lot) of wasted CPU cycles multiplied by the thousands of packages that use autoconf. For the majority of packages that don’t patch configure.ac or Makefile.am, it’s nicer to use a preprocessed tarball and check that you can reproduce the same autoconf output when adding the package to the package manager, because then it only happens once.
I would hazard a guess that there are far fewer people these days who download a tarball and `./configure` `make` `make install` than there are distros (who often need to patch) and developers (who will be working from git anyway).
The situation is deteriorating further as some projects make no releases at all, assuming users will add the project’s own package mirror to the user’s trusted package repositories, or use Docker.