Lots of people ride track frames on the road, but with only one gear.

Most manufacturers have relaxed the geometry of steel track bikes as more and more riders began using them on the road. Aggressive 75/75 geometry is now reserved mainly for carbon and aluminum frames which are ridden on the track. There are exceptions.

I ride one of the slightly relaxed steel "track" frames on the road regularly - 3 or 4 times each week for rides up to 50 miles. 2015 Bianchi Pista. Was in a 26MPH paceline last week. Loads of fun! Mine actually has two gears, 16 and 15 tooth cogs on either side of the rear wheel.

Cons: no cage mounts and have to carry bottles in the jersey pocket or use a clamp on mount. I have to take the wheel off to "shift".