I think that what you call "twee", my generation would call "memes". Phrases like "gestures broadly at everything", "this" and "because reasons" originated on Tumblr, and became linguistic memes. Their proliferation into serious discourse is because of social media, phrases like "unalived" making their way into normal conversation etc because of censorship on social media. But I've noticed myself using memes as "in-jokes" with my real life friends.