Theory is a big subject and a fascinating one, but at the end of the day it's an analytical tool... Not a rulebook. It helps formalize music into something we can write down and discuss rather than just hear in the moment.
Was just typing something similar - when used correctly, theory shouldn't be seen as a set of rules to avoid or bypass creativity ("in x sutation, y is the right approach") - IMO it's mostly helpful when new creative ideas need to be communicated between musicians. That goes both in giving and receiving feedback.
For this reason, a bassist in an originals band, or even just one that only follows notation, doesn't really have much of a need for theory even though it can prove helpful. It's also why it's essential for studio musicians or higher level instructors who need to constantly give and receive feedback.