People who use knickknacks as decoration have a need to fill space just for the sake of having something there.

This is a conflict of idea, you’re suggesting buying nick nack’s to fill space whereas my suggestion for buying nick nacks is because I like them. There is a difference between finding objects to fill space and finding space to hold objects.

Obviously to extremes this can be seen as hoarding nature so it’s not without its issues but in general many minimalist styles I’ve seen don’t truly follow this philosophy. Often you find a coffee table that holds one item, but the item is not needed for the room, a coffee table is just a staple of living room design. On another side you will often see throw cushions and rugs in these design but they hold no intrinsic value other then pulling a room together