The point was not to hide memory from programmers who "had a clue" if they went looking. During production, most programmers on the team would be focused on delivering features they were responsible for and fixing bugs. If they were doing perf or memory profiling it would mostly be focused on whatever feature they were implementing. Only a few people on the team, perhaps only the lead, would be looking at global memory usage / perf on a regular basis and even then they'd mostly be looking for regressions. If anyone did happen across this they'd probably go talk to the lead (there might even be a comment directing them to do so) and be let in on the 'secret'.

At the end of production coming up to release is when there'd be a wider focus on general perf / memory usage to get everything to fit for the final release build. In my anecdote above, the reason I happened to find an example of reserved memory was just that I happened to be the first person to go looking in the right place with the right tools, not due to any particular skill or experience on my part (I was pretty junior at the time, this would probably have been around 2004 towards the end of the PS2 / Xbox console generation).