Linking root domains and rankings

I've seen on several sources (Moz, Backlinko and coff Neil Patel) and I've read that the number of root linking domains is more responsible of the High rankings than the number of backlinks. I don't understand tho if the number of linking domains include both the domains that gave you a nofollow and those that gave you a dofollow, or Is only restricted to number of domains that gave you a dofollow backlink. Anyone has answers/experiences to share?