Currently HubSpot only allows HubSpot CMS Admins to create Topics and these are only able to be used for Blogs.
Most Enterprise Grade CMS enable Admins to create Site or Mult-Site Taxonomies and Classifications these can then be applied to ALL Website Pages, Landing Pages, Blog Pages etc. this helps CMS users to find content and enable users to find content.
The ability to create a set of nestable Classifications, Categories and Tags would really help for example
HubSpot MarketPlace is a good example of how this could be applied
Classifications = HubSpot MarketPlace
Categories = Marketing, Sales, Customer Success, Finance
Tags (Features) = A/B Testing, Personalization, Collaboration