There are a number of cities in the valley that all consider themselves the same community. I think this is the same sort of concept. The list appears to be based on where the companies were founded not where they currently have presence.
While Detroit has been trying to resurrect itself, to take just one for-instance, Ann Arbor has just gotten on with life, and slowly but surely the rest of the region is following. Even if Detroit becomes alive again it will be a while before it culturally dominates the area again, if it ever does.
In terms of the sorts of things that might be of interest to Hacker News, there's not much point to resurrecting Detroit and to be honest I don't understand the HN obsession with Detroit. Just drive an hour west. What people don't seem to get is that it really is Detroit that is dead/dying; the Greater Metropolitan Not-Really-Detroit-Anymore area is getting on with it. I will not say thriving, because that isn't true, but only Detroit and the aforementioned absorbed municipalities are dying.
Look, if you love it, great. But don't go giving the rest of us a song and dance about how wonderful it is, because there's more vibrancy in a chunk of San Jose I recently stayed in, considered to be a relatively dull Silicon Valley city, than in downtown Detroit. If you don't think it's a city in a very bad place, there's a word for that: denial.
Also, I remind you, I'm talking about Detroit, not the region. The region is getting on with life. Detroit is still struggling for breath, and it has become clear that the fate of the region isn't at all particularly tied to Detroit, because the rest of it isn't sinking with it. There's literally no possible way to have a more vivid proof of the fact than by demonstration.