There is a place for simple hot sauces, because you don't want to add additional flavours. Sometimes all you want is straight up chilis.
More complex hot sauces might include dried shrimp, fermented soy, lemon grass, dried mushrooms, but those flavours might not be desirable in some dishes. And some dishes require specific hot sauces because they are an integral part of the flavour profile (Mapo tofu, Tom Yum).
I would just like to interject for a moment. Mapo tofu does not use 'hot sauce' as understood in the common parlance. It uses doubanjiang, a very specific fermented paste of chilis and broad beans. It is not saucy; it's very thick like gochujang. I take issue with calling doubanjiang hot sauce and I really don't want anyone to try to make mapo tofu with normal hot sauce.
There is a place for simple hot sauces, because you don't want to add additional flavours. Sometimes all you want is straight up chilis.
More complex hot sauces might include dried shrimp, fermented soy, lemon grass, dried mushrooms, but those flavours might not be desirable in some dishes. And some dishes require specific hot sauces because they are an integral part of the flavour profile (Mapo tofu, Tom Yum).