But the problem is that the flow between those personas is not bidirectional.
Again, generalizing a lot here, but let's call them Cold and Warm personas.
If a Cold receives a Warm message, generally speaking the worst they might feel is that the other person is being inauthentic. In my experience, what usually happens is that they just filter out all the niceties as extraneous and get on with their day. As time goes on, they won't necessarily change their communications or relationship with that person -- after all, they're still getting what they need from them.
On the other hand, if a Warm receives a Cold message -- if they notice a pattern of receiving Cold messages -- they might take that as standoffishness or outright hostility. Even if it's not that negative, the Warm simply won't build as much trust as they otherwise might. They aren't getting what they need.
So in this scenario, if everyone communicates as they naturally would, Colds don't notice anything wrong, while Warms feel like they're actively missing out on something important to them.
I would also note that, again in my experience, most people who describe themselves as Cold communicators ("I don't want fluff, just communicate directly with me") actually really appreciate people who communicate with lots of social niceties. They respond to them more quickly, they're willing to explain misconceptions, and so on. They just don't think it's because of communication style.