Computerworld - https://www.computerworld.com/article/3280102/enterprise-applications/6-tips-for-planning-sharepoint-hub-sites.html#tk.rss_all
Hub sites are the newest intranet building block in Office 365. They are now available to all Office 365 customers, including enterprise, education, and government.
In the new flat world of modern SharePoint, each unit of work gets a separate site collection. Hub sites allow us to eliminate the inflexibility and governance limitations of “dreaded” subsites, while providing a way to replicate one of the key benefits of subsites — a way to create a shared experience among related sites. Hub sites can help kill subsites, but not without a little planning.