"...Our system in fact cannot take you to any specific Hub..."

Perhaps what is needed, is a link on the home page pointing to a page where all the generic (non-company-specific) hubs are linked to. Currently those hubs are all well hidden from the average user, unless they become aware of them through other means.

Or perhaps the "Marketplace Directory" box on the home page could be expanded, by adding a fifth tab for "Generic Hubs" or "General Hubs" to the existing four tabs.