I don’t know the etymology for “platitude” offhand, but I can only assume it refers to a too-short, too-simple, utterly inadequate way to describe this:
This is a complex thing. Once it’s out there, how do you deal with it? You can’t just be like oh, it’s a platypus. It’s a hoax. You have to dig deep. Why is this thing so discomforting? Why is it the way it is? Why, dear God why, is it poisonous?
A platitude is what is said to you by a person who does not care, a person who is not ready to turn good intent to good content. Such a person is willing to name it a platypus and peace out. A platitude thinks its stark simplicity makes it look sufficiently profound, and that its deployer can now just walk away having done a good deed. Really, a platitude is an explosion without the burning fuse of sincerity to build up to it. Or, you know, keep people from getting blown up.
Life isn’t fair!, somebody self-righteously ventures in order to justify a unfair situation or action much smaller than life. Do you ever think “Oh man, you’re right”, or do you hope their car gets stolen?
Believe in yourself! Halftime speech filler. If you’re being told this, you probably look in the mirror and see not a whole lot worth believing in, so this alone is gonna bounce right off you.
Everyone is crazy! This one is just sinful. There’s 8th grade purple cheese monkeys “crazy”, there’s serious institution “crazy”, there’s the advanced “the whole world is just crazy, so anyone who’s a part of it is too!” Dave Chappelle and I hate the word crazy. Especially because it’s unkind to that middle group of people who actually need a special kind of help. You can’t just sweep away the bizarre and sometimes perverse patterns of our lives just by going “HURP DURP I DUNNO, HUMANS SURE ARE WEIRD.” Dogs do that. Dogs do that when they have to push adult humans on Fisher-Price tractors.
Important: This doesn’t mean that any short sentence is free of substance or sensitivity. How and when words are said is key, not just the words themselves. If you are being told “don’t give up” by a tearful, Atlas-bodied swimmer holding a gold medal in one hand and your shoulder in the other hand, you can probably believe them. If you are told “everything is going to be all right” by someone holding your hands and looking you right in the soul, you can probably believe them. You can feel when someone means something, and when they want you to know they mean it. Chances are you can even get them to keep talking. That’s when what was once a platitude evolves into the title of a new chapter.