Historically in autoconf codebases (which PostgreSQL is) `make dist` is done: a) after `./configure` (so you have a Makefile, naturally), which is b) after `autoreconf -fi` (so you have a `./configure`). This allows the dist archive to contain the outputs of `autoreconf -fi` so that users need not have autoconf installed and they can just run `./configure`.

Switching to `git archive` is fine, and you can add files to that, but https://github.com/postgres/postgres/blob/master/GNUmakefile... doesn't. So, I guess users now _have to_ run `autoreconf -fi`? No, because those are now committed in the source tree (https://github.com/postgres/postgres/blob/master/configure).