I'm the opinion that we should aggressively flatten all tags for hardware. But I'm open to an explanation of how in practice it works well on another site. Or an example where it works well here.
The example I have is MacBook and MacBook Pro and Air and such. Do you tag the generation or the size of the screen or the CPU or if it has SSD or HDD when that was a thing? It ends up taking two to three tags for the precise questions when you can usually search the MacBook tag and then the term for what you really want.
Thinking more deeply, people really don't often want to ask about a MacBook pro itself - it's almost always going to be about upgrade or port or what not and then we could be tagging on the specific item in question for the best locality if you're looking for a narrow tag to follow or search.
The side effect of general tags is that the wikis require less maintenance if they merit a tag wiki or summary at all. The wikis should be about how to use the tag and duplicating usage for MacPro across all the models Apple has and will release seems like a lot of duplication of work for little payoff.
Good question though +1 for raising the discussion. I can see it might not be an easy one to pick an answer for many. Even though I lean one way - I'm open to new inputs or opinions on this topic specifically and generally.