Well, there you said it. Without the adventures Freeport is a setting, not a campaign.
I guess it's just differing definitions. The thread started from comparing Freeport series of modules and the Shackled City. Now both of those are campaigns, with the same caveats - the latter modules expect certain level of xp from the previous ones. When you move to comparing SC to Freeport series + Freeport campaign setting, it's comparing apples to oranges. Greyhawk campaign setting is to SC what Freeport campaign setting (main book) is to the Freeport series. So yeah, it supports more campaigns, but IMHO SC fits the definition of a campaign better than a campaign setting.
This shouldn't have been a reason for me to get this argumentative though, so please accept my apologies