And how is someone rushing for the flight who is not familiar with the layout of the terminal supposed to know that?

When you head from the ticket counter to security the big sign says "All Gates", which is the clear way you tell people that regardless of your gate, please walk this way.

However, after security the signage does not say "All Gates", but instead there are various directions in which one can walk, and signage with listings of various specific ranges of gates followed by arrows. Perhaps all of those arrows point down the stairs in the same direction- all I saw (and what most people in a hurry would see) are various signs with arrows pointing to various gate ranges - and I had no idea what gate I needed. If in fact all gates are downstairs, and they are not going to put monitors after security, then the signage should continue the convention that it starts with before security and the signs should say "All Gates."

Also, as I mentioned in the original post, I may have been suckered in somewhat by the Schiphol-ness of the terminal, as Schiphol has monitors at every fork in the road, including right after security.