Hide Groups from a Guest User

From my perspective, your approach should be the standard and not the other way around.
I come across this article many years later and still: Group membership enumeration is possible and causes risks for organisations. It's easy to identify C-Level or Admin accounts by just poking around in a default setup.

I found some settings via Powershell to hide group memberships, but would assume that many customers share their memberships without knowing it. The description left the taste that I would assume something "super secretive", but it a general measure which is nothing special.

The term "non-hidden groups" causes confusion to me, since it leaves the feeling that an admin would have to "unhide" memberships and causes a wrong sense of security.

Edit: Ah and of course: There is a more restrictive option now, but it isn't default. Which leads back to poking around in default setups.