In Avowed they focus on management of weapons and armor as a tool for discretionary encumbrance. These items directly effect gameplay and therefore matter more to the player.
The smaller items that are all weightless effect gameplay indirectly and would make managing encumbrance a bit more convoluted.
Seeing as Avowed is more of a boiled-down rpg than what it is directly compared to (Skyrim), that extra time spent managing trivial items in an inventory just seems like a waste when the game itself is really trying to be a streamlined version of meatier rpgs.
Yeah it really just works kinda like i said, but the game also does a good job of organizing items so you can easily tell if you have more than necessary.
Another example of streamlining is the stamina system. It is limited in a fight to create a sense of balance and progression as you upgrade it... But when running around the world it is unlimited.
This is nice because it does not hinder traversal and imo worrying about stamina as i explore takes more away from the experience than it adds to it.