Originally Posted by Spoonrobot

"Hybrid" started life as a marketing term for a drop bar bike that was neither road nor mountain, eventually it came to refer exclusively to flat bar bicycles. At which point "drop-bar hybrid" had to be developed to compensate for this "third" type of bike. This happened fast, 1988/89 and by 1994 "Hybrid" was known to exclusively refer to flat bars. Drop bar bicycles blending road and mountain wandered homeless of marketing category from Cross Terrain, to Cross, to eventually Cyclocross as a generic term - eventually turning into Gravel/Adventure/Etc in the early/mid-2010s.

You'll note that Mr. Overend does not refer to this bike as a "drop bar hybrid" because that phrase didn't make any sense in 1989.