It's a rhetorical device. Babies wouldn't understand it. When used in earnest, it tends to sound breathless and dramatic, probably because that's how trashy jo

It's a rhetorical device. Babies wouldn't understand it. When used in earnest, it tends to sound breathless and dramatic, probably because that's how trashy journalists use it in headlines. It tends to be used as a kind of statement of passive resignation. It's deliberately the most colorless, blandest, simplest way to possibly express the idea that it expresses. Whereas you might otherwise say "well that's new" or "ugh, I forgot about X", you might say "that's a thing." It also seems to be somewhat of a recurring meme, I remember reading an article showing how this "a thing" phrase makes the rounds every couple of decades. I think there are some really ugly phrases out there now ("ask" as a noun instead of "request" or "task" is kind of nauseating). But lighten up a little bit, some people like to have fun when they speak. Think of it like absurdist humor, rather than baby talk. I know it's trendy in some circles to claim that adults have become infantilized or whatever, but I don't think that's what's happening here.