Yes, but you can just carry encrypted hard drive with you. Hiding encrypted data is useful pretty much only for legal reasons. You want to take it across border and are worried TSA agent will force you to decrypt it or something. What is safer in that case? Carrying a USB stick with hidden encrypted partition or not carrying anything at all and downloading the data later? I would say the latter. Smuggling encrypted data through custom checks into a war zone with limited internet access is the cool but unlikely spy games scenario I was talking about. Encrypted microSD card would be even more secure in that case.

that's like saying "password managers require a password so I don't see the point"

Those recommendations are for protecting data you want to stay a secret; it would also apply to unlocking this fancy USB drive, as a best practice.

The USB still has advantage in that no one will compel you to unencrypt a drive that they don't realize is encrypted, which can be a pretty significant advantage depending on who you're hiding the information from, or why.

you don't have to boot into some special live OS to mount the hidden volume. It can be mounted just like a normal encrypted volume.