Every program attempts to expand until it can read mail. Those programs which cannot so expand are replaced.
Zawinski's 1995 observation. Its modern form is that every successful application accretes a chat feature, and the underlying claim is about the gravitational pull of communication features.
In practice
- A document editor adds comments, then mentions, then notifications, and is competing with the chat tool nobody set out to replace.
- A project tracker's most-used feature after two years is the comment thread, and the tracking is what people tolerate to get it.