Facebook diplomacy was coined in 2011 during the so-called ‘Arab Spring’ uprisings in the Middle East. Social media platforms were used to mobilise protestors and coordinate protests. It was the main channel of communication that bypassed central government controls.
Later on, the term Facebook diplomacy was used in the following context: a tool for communication with foreign governments, as a public diplomacy medium for outreach towards foreign populations, as a consular tool to keep in touch with citizens in a foreign country, and a tool for cultural promotion.
Today, these uses of Facebook and Facebook itself have become mainstream. Thus, the term has fallen out of fashion since there’s no need for it to describe a new phenomenon.