2. The hockey stick is mainly needed to deal with impatient investors, not in itself. If you had a stable supply of money, you could grow over any number of years, but without showing the right graph its hard to raise money.
3. At least in SF you have a pool of clever engineers or cofounders. Its not like that in all places.
I think it really depends on what kind of company you are building. If its something startup oriented like APIs, or any fad (like IoT), SV is your place. If you're in a capital intensive business, SV is again you place. If you're solving problems for tech companies.. then again. And if its social, you'd be cool if you're in SV and backed by an SV firm. You need the networking and coverage to succeed, and its much easier to come by in SV.
If you're making enterprise software, real hardware products, SMB tools and apps, then you can be anywhere else really.
Besides, SV has that startup vibe going for it. Its not quantifiable but it sure energizes to some degree.