Except that is not what the book teaches at all. Sometimes people can’t take the advice of “just be a better person and care about other people” unless it’s explained to them more specifically and anchored to their goals. It’s not because they are inauthentic, it’s because they are lacking skills and understanding.
I actually crashed out semi-recently about this exact thing, quit church and all and was genuinely surprised when the people who were speaking politeley to me reached out in a genuine, non-public and non-coerced way.
I don't think the word "inauthentic" quite captures why people react negatively to this sort of communication.
At least part of it comes from the fact that this particular style of "kindness-is-cool-coded" (for lack of a better word) communication happens to be the preferred style of insanely passive-aggressive people who take it upon themselves to brutally sabotage anyone who they deem unacceptable. It can also feel like you're being lead on by someone who actively dislikes you but is too polite to say it. Or you just start second-guessing every single thing they say and do.
But honestly, there's a pretty sizable minority of people who are repelled by this type of person and if you're naturally bad at reading the room you're probably better off making friends with other people that say and do dumb things.
I know I went through a "How to Win Friends and Influence People" phase when younger and basically ended up just putting off a whole of people.
Culturally many Australians have an ingrained and likely healthy aversion to feeling they are being "handled" or manipulated in some manner.
Likely stems from a hundred and fifty odd years of the "always British" types swanning it over the "this is where we live and we love it" crowd.