Chat message sounds became a staple of online video because messaging is now a central part of everyday communication, and creators needed a quick audio shorthand for it. Rather than being tied to one app, show or meme, this type of notification is used across shorts, reaction videos, skits and edits whenever a conversation needs to be shown rather than explained. Its staying power comes from that familiarity: almost every viewer has heard a similar tone in real life, so the meaning lands instantly and needs no caption or setup.