>
> While that's as may be in general, the docstring for user-emacs-directory
> (in my Emacs 28.2) states "Note that this should end with a directory
> separator." specifically, which I take to be part of the variable contract.
> Doesn't that imply that it is Emacs's responsibility to handle that aspect
> if setting user-emacs-directory based on a file name that may not satisfy
> that predicate?
>
> -RTT


Correct.  consistency and standardization on such matters is better for
overall user experience.