Why "stay away from your back brake in the rain"?

In my situation, I hit the front brake ... the next thing I knew my front wheel was turned around facing me, and I was thinking ... "THIS is NOT good!" I've been told that I would have probably gone down no matter what I did in my situation, but that I should have gone for the rear brake instead of the front brake.


Also, someone suggested descending in the drops. If you sit up, don't you provide some extra wind resistance which can slow you down a bit?


I hit 51 km/h on a descent today. But it was a very straight descent, on a nice dry sunny day, on a good road.