There's no need for limited (and thus frigginly annoying to manage for casual players) number of slots when you have weight to limit what you can brought with you (for the reality check to me inventories are magic crafted by default or a gift from the various deities to their followers or creations. that's the only way I can explain why killing a vendor, or any npc to be fair, never gaves, as loot, all the actual stuff they have. The inventory is not a bag or a container wich, indeed, have a limited number of slots, but a kinf of a pocket dimension, that still is limited by weight).

In my party the int/wis/char based can brought up very few items if they take up a baril.

The weight system is still a puzzle to me. There is no direct correlation between the dimensions of objects and their weight, let's take for example the health positions, those are litteraly bottles big as two or three litters bottles. Furthermore while in DOS and other games when you reach the limit of weight your strenght allows you feel the overweight malus, in BG 3 I noted how characters can go over the 50% of the maximun weight set in the character tab.