There are soy sauces and there are soy sauces but they are neither equivalent nor substitutes.
Historically, soy sauce arose in China but it spread across South-East Asia and then the world. As it spread, the production became local and its irresistible umami flavors were tweaked to local tastes.
That means that Chinese, Japanese and Thai soy sauces (just to use three as an example) are totally different. Even within a single culture there are multiple kinds of soy sauce that have different end uses. This parallels the equally different kinds of fish sauce each tweaked to local tastes.
The CC can hear the screams from the peanut gallery already.
"You mean to say, that I must now stock different kinds of soy sauces?!? Are you nuts?"
If you want to get the right flavors then yes, and yes the CC is nuts. (Not much doubt, was there?)
The point about the "right" flavor is made most memorably in one of the episodes of the serialized food manga Oishinbo (美味しんぼ).
The name is a portmanteau word between oishii (= 美味しい, delicious) and kuishinbou (= 食いしん坊, glutton). On the one hand, the manga has a simple format which is important in a serialized format just like a sit-com, which is why it ran for 30+ years, but it's so heavy-handed and Oedipal that Freud might have objected!
However, it's both excellent and makes important points. At one point, the father upstages the son by making the same dish with the same ingredients but using Chinese soy sauces rather than the equivalent Japanese versions because the dish is of Chinese-Japanese origin not truly Japanese. (As stated, heavy-handed but still with a point.)
If you choose to engage in this journey, these are not expensive products and they store indefinitely in a cool and dark environment so it's not as big a burden as it sounds.
How many can you get away with at the bare minimum?
The CC is guessing between four and six — two for Thai food, one or two for Japanese, and one to two for Chinese. More if you want to cook Indo-Chinese or Filipino.
Just don't shoot the messenger.