But most people who are invested in small talk will be giving the signals they think the other person wants, making it less useful than not talking at all.

I don’t think this is true. When I engage in small talk, I don’t see it as me bending flexibly to the conversation partner’s wants. I’m testing to see if there are common overlaps that we can talk about, and talking for the sake of being entertained. If the other person turns out not to be a good conversation partner for me in that moment, I don’t think anything of just moving on. I’m not trying to please them, I’m trying to enjoy myself.

I can’t imagine I’m in the minority here.