I got sick of the constant quick travel back to merchants in BG3 and decided to just install the mod that multiplies my encumbrance by 9000x. the item management in that game is a giant pain and the gold economy plus encumbrance is an artificial barrier to getting them from merchants that simply adds playtime for no actual benefit.

Realistically speaking, if you want a useful encumbrance system, you should be thinking: what is the goal of an encumbrance system in the context of this game?

In BG3, it serves a few purposes:

1. physical consequences. reduced movement speed, damage from jumping, etc are all part of D&D rules, which is useful when you're in a kind of situation where, say, you need to get a giant boulder across a huge gap and put it on top of a button that opens the gate while in combat. but outside the context of combat, doing this is meaningless, as the player can simply overcome this problem with time, which is annoying more than fun.
2. limit access to the number of options a character has when confronting an encounter. it's not feasible to carry 99 potions of greater healing on you, and encumbrance is a general strategy that prevents this from being as effective. at the end of the day it does not solve this problem
3. express limitations on what a character can do with their environment. encumbrance affects how much else you can carry, such as throwing a big rock at an enemy to do a lot of damage. this is irrelevant in the context of inventory vs. how much you can affect your environment; it can easily exist independently of an encumbrance system.

I don't like encumbrance in games in general. It makes games more fiddly, and forces the player to engage the system with no real addition to the fun of it. Limited inventory slots are similarly frustrating in games to the scale of Baldur's Gate. BG2 solved both of these problems by giving the player a billion bags of holding, which also had the added benefit of making inventory organization easier in a system that was largely left the same from its predecessor since it probably was built on the same codebase. BG3 had no such codebase restriction, and its type sort system sucks (the search bar is a lifesaver). Encumbrance very much feels like a "This is how it works RAW in 5e, so we're going to do it this way" decision, which is funny because in plenty of other situations the devs decided to stray away from RAW to make the game a lot more approachable.

I don't know if the goal of encumbrance is to prevent players from taking everything as much as possible or not - but if it is, it utterly fails at that goal