Bicycle definitions are slowly beginning to blur and morph into something they never used to be. For example, some of yesterday's mtbikes look like today's hybrids. Some dual suspension hybrids look exactly like certain 29er ht mtbikes to me. I always thought that a road bike had drop handlebars and skinny tires. However, if you look at the salsa fargo with its fat tires...Is that really a road bike?
Look at the now defunct trek sawyer. It looked more like a cruiser, but it was considered a mtb. Sheesh!