Commuting distance over time. Touring distance over time. Those are things that a couple mph stretched over a year of commuting or several long days in the saddle on vacation could make a tangible difference to somebody who doesn't race or group ride.

Both could be situations where someone wants to know the difference in speed a road bike or hybrid have.

Saving two minutes each way on a commute over 200 work days a year is almost saving an entire waking hours day of your life! If touring on vacation, the difference could mean showing up 1/2 hour later to a destination for cleanup and dinner. It could mean over a long touring vacation being able to stretch the destination out.