Perhaps the OP means that by having brakes he would not learn to really spin out those desents and instead just use the binders.
I have BOTH a F and R brake because around here there are often turns at the bottom of some of the steep hills. Using only a front brake might cause the bike and rider to understeer into the other lane. I use quite a bit of rear brakes on the sharp downhills to help rotate the back end of the bike. Since we can't lean over as far as a freewheeled bike I find this necessary to do this.
Lastly, on spinning out the downhills, I find it best not to think about pedalling and just relax and let it wind out and it also helps to look much farhter down the road too. I saw 36 mph on a downhill today and that was in a 74.3 gear inch drivetrain. Gerry