There is a significant difference in experience between Copilot Basic for a M365 user whose IT admins have blocked integration capabilities with Sharepoint content vs Copilot Premium for a M365 user whose IT admins have allowed integration capabilities with Sharepoint content.
Microsoft is better off not allowing copilot basic because of the reputational harm it will do. Not that they are thinking through copilot rationally
A recent funny story on this topic: https://idiallo.com/blog/what-is-copilot-exactly
HN discussion: https://news.ycombinator.com/item?id=47603231