I've noticed that not all steel forks have those drain holes. Of the 4 bikes in my garage, only one has drain holes, and it's a lower quality bike than the other three. I suspect that high quality fork blades are sealed with an inert gas (and therefore no water vapor) inside. So KnottedYet, I think you can safely buy a full steel frame without hysteria. Bottom brackets don't tend to rust given all the grease packed in there.