The original use-case was an engagement mechanism.
Their statement is:
> So, on September 12 we’re going to retire this little-used feature as we work to develop more effective fan engagement tools for creators.
They are going to replace it with a new thing to cover the engagement mechanism.
It is true that with things like Google Reader it was not being replaced. But in this case their statement declares an intention to replace the retired feature with something else that helps solve the engagement scenario.
