wrote:
[..]
It is somewhat bizarre. Most of the things he packs (including writing
paper!) he could easily buy at his destination, per his own
suggestion...

The things you need depend heavily on the activities you plan to do.

I often travel with light pack, but I'd never leave my LED headlamp and
my silk sleeping bag at home. I'd never bring an electric shaver or 5
pairs of socks or underwear (I'd rather wash them every day ...).

other important things I always carry which proved to be useful:

a small first aid kit, a simple rope and a tie wrap ...

things i can easily leave at home:
.) any item that requires a battery (incl. mobile, camera etc.)

Manfred