Well I disagree, so I don’t think it’s objective. Another goodie is when installing an update, macOS only shows that you can cancel the update if you hover over the progress bar or where the cancel X would be. If you just look at the window, you think there’s no way to cancel and that you need to ride it out. You just have to happen to hover over the right element. There’s no reason for this. macOS is absolutely full of little things like this that are hidden in the OS. iOS does this as well. Going to the settings screen, you gotta pull down to see that there’s a search bar. Again no reason for that. Both macOS and iOS are very inconsistent and hide all sorts of settings, behaviors, etc. Another example is that I can’t even adjust my external monitor’s volume and brightness from the OS because Apple wants you to buy their monitors. And all that’s ignoring the portion of usability from things in the OS just not working or that break.
There is a really compelling reason on iOS: saving screen real estate. And the top-hidden search bar is convention now, just like the pull-to-refresh gesture. Discoverability is an issue though, I agree. But unnecessarily hidden? Disagree.