Installing "one Perl" on Big Iron is exactly the reason why the things are distributed across the various directories. If you plan it right, you can run "one Perl executable" and have all Perl libraries mounted under one NFS tree, and the binary Perl extensions will pick up the correct architecture based on the arch string.

Of course, in practice this only works out in rare cases, and you already know how this can become a configuration nightmare. Nowadays, disk storage is cheap enough to replicate (or install) Perl to every machine instead of launching Perl from a network share.