I think the question and the answer conflate two very different threat models.
Back in the day, everything of interest was on the device, and to be search-resistant, it was necessary to encrypt and hide it well. And most answers still seem to assume this is the case.
Nowadays, though, almost everything of interest is stored in the cloud and what the cops/CBP/three-letter agencies want is the credentials to access those. Sure, you can make their life a bit harder by logging out of everything, so access is not completely trivial, but they can still stick you in detention (or worse) until you cough up your passwords, regardless of what is or is not on your device. And the only way around this is to never show up on their radar in the first place.
This is not true. Current CBP policy instructs officers to only inspect data residing on the device, not to probe your online accounts. Obviously any data loaded in apps that are already open when you hand over your phone are fair game, which is why the advice is to turn off the phone before handing it over.
Back in the day, everything of interest was on the device, and to be search-resistant, it was necessary to encrypt and hide it well. And most answers still seem to assume this is the case.
Nowadays, though, almost everything of interest is stored in the cloud and what the cops/CBP/three-letter agencies want is the credentials to access those. Sure, you can make their life a bit harder by logging out of everything, so access is not completely trivial, but they can still stick you in detention (or worse) until you cough up your passwords, regardless of what is or is not on your device. And the only way around this is to never show up on their radar in the first place.