I don't know quite how the term started but...
When I was young, my parents would have dinner parties. Sometimes it was for a holiday (usually around New Year's) but often it was not attached to any specific occasion. My mother would carefully balance the menu and the guests, cleaning and shopping for days beforehand. Because this was the 70s, the height of chic vis-a-vis "nibbles" in Smalltown was Bugles and sour-cream-onion-dip (and if anyone knows where I can get a box of Bugles... not that they were great but the trip down memory lane would be fun).
Anyway, some of the guests were people my parents wanted to invite, and some were always invited because of what my mother called "retaliation."
Retaliation for what? Inviting my parents in the first place. To this day, she'll say, "We have to retaliate with the [name of hapless guests]".
Today I'm hosting a small gathering to show off my house. There are colleagues from work, people I hold near and dear to my daily life, and there are friends from other areas of my world. Family is included. And yes, like the good daughter I am, I am retaliating.
Take that, friendly people who've opened your house to me before!