Private symbols vs property attributes

[Andreas Rossberg]

On 8 February 2013 00:41, Allen Wirfs-Brock <allen at wirfs-brock.com> wrote:
> Note that the enumerable attribute really only affects for-in enumeration (and Object.keys), neither of which enumerates symbols anyway.  That, means that the enumerable attribute really has has no current meaning for symbol keyed properties.  That means we could probably reinterpret the enumerable attribute as a "private" attribute for such symbol keyed properties.

I wasn't aware of that, and don't understand it. Why wouldn't I want
unique (as opposed to private) symbols to show up? Is that special
casing for backwards-compatibility?

/Andreas