And in most cases, the coil might actually last a lot longer than the points and condenser will. You do run the risk of overheating the coil, of course, and I do know of people burning them out relatively quickly, but I've run both stock and aftermarket low-volt coils for quite a long time on 12 volts and although I burned out several sets of points and condensers, the coils kept working.
Not that you should, but in an emergency...
You can buy modern coils that run on either full voltage, or reduced voltage (through a resistor), but you can't really run the higher powered setup (reliably anyway) if you still have a points type distributor.
Paul