A lot of people will look at a road bike and see only the road handlebar, and think the reach for the drops is what makes a road bike a road bike.

But road bikes evolved primarily from competitive riding, where riders of widely-varying ability have long wanted to at least give their own "physical endurance level limits" every chance at finishing a grueling ride, and in as little time as possible.

Thus the principle road bike virtue comes when the rider is positioned in the saddle such that rising to a balanced "standing" position can be as effortlessly and quickly done as possible.
This requires a somewhat-forward seated position, and allows the rider both to let their legs "spin" (in the saddle) and "extend" (out of the saddle), as such needs are imposed by undulating terrain.

As well, a forward seated position spares a rider's energy by being more aerodynamic, and the resulting somewhat "forward-rotated" lower half of the rider's body allows the rider to maintain a lower tuck while not having to bend as sharply at the waist, improving both comfort and power output.

The out-of-saddle position and fit, as determined solely by the bend and positioning of the handlebar, is critical to the rider being able to straighten their torso, lean forward and thus to use their entire body's range-of-motion in order to allow the knee joints to operate within a less-sharp angle, in order to effect much greater force at the pedals with far less stress at the knee.
Not being able to quickly and effortlessly transition to a forward-leaning standing position sharply limits how much power that the rider can maintain without knee-region stress and injury, thus also greatly increasing the need for low gearing in order to conquer hilly terrain!

Remember that a balanced forward-leaning position above the bottom bracket is directly related (proportional) to the force/torque that is applied to the pedals, thus a "rearward-fitted" or touring-style road bike will thus need much lower gearing, and the end result no longer resembles an actual road bike.

Schwinn took what were layed-back cruiser bikes with 27" "narrow" tires, and fitted road handlebars to them. This was the Varsity/Continental recipe.
It takes about every trick in the book to get a hard-charging rider properly fitted to one of these bikes, and still makes for an extra dose of upper-body workout so as to hold oneself in a needed forward-leaning position when riding up steep hills. It becomes all one can do just to keep their knees from hitting the handlebar ends.
But those bikes were/are great for riding at lower intensities on more-level ground. Sound familiar?