Politeness > accuracy & honestly is a very common preference, but not mine.
Your sentiment is a really common and insidious one that way too many people use to feel smug and "rational" about being mean
Careful - you'll cause some heads to explode before they can retreat to their safe spaces...
These concept are pretty much orthogonal. While I don't disagree that insistence on politeness can get in the way of good discourse, it is an all-to-common mistake to read or promote lack of politeness as a signal of honesty and accuracy - which manifestly isn't the case.
It's also often done in a lazy way. Which doesn't imply the thinking is also lazy, but there is a good correlation.