It's absolutely critical. While it's unrealistic that Maomao somehow ends up involved in some many things, otherwise there would be no story, but that desire to stay out of any business that's not her business is something people in such a setting would need to have to stay alive. Back in the day, a person's life was super cheap. Maomao's old man, as well, was doing his best, but was punishned nonetheless. I reckon Maomao would have been taught that attitude also by the people in the red lights district. It would have all sorts of customers, including important officials and other aristocracy, so the employees there really should mind their own business, lest heads start rolling.