Lying to people in order to "spare their feelings" is a selfish cop-out imo. I think when people do that, it's more about them being inept and immature rather than having genuine concern for the other person.
That said, feelings do matter. There are ways to relay the truth to someone without being a dismissive asshole about it. So people who do the opposite and say shit like "i don't care how i come off, the truth is the truth" are equally annoying.