It don’t use packs in the same way or for the same things and the features they require vary accordingly. For example, some people use a hydration bladder, some people use bottles. It specially creates parts of the pack that can be removed to produce a personally optimised LeanWeight product.
Eventers can also get their scissors out and remove excess features in the hunt to save further grams without invalidating guarantees in other areas of the pack. It’s quoted LeanWeight is the pack weight less all removable parts but before scissors.
LeanWeight chassis system and technical fabric selections provide strength at minimal weight for lean packs that can be depended on in uncompromising situations.