Sure, some jobs will go elsewhere, but there are big returns to being where everyone else is. This book does a good job explaining why:
There are 'network effects' at least in terms of jobs and that environment. You'd have to convince a bunch of VC's to move to wherever along with a bunch of tech workers.
Pretty much it is a networking effect issue. The same reason why you are posting this on hackernews instead of reddit. Physical proximity matters a lot, even when work is digital.
http://en.wikipedia.org/wiki/Bologna
I suppose that compared to Tokyo, most anything could be considered a small town, but in Italy, Bologna isn't.
Quibbling about details aside, I think your point is a good one, although I also believe there are definitely two sides to it. The case made in this book is convincing that cities are a lot better for the sort of "spontaneous idea contamination" that can lead to big things:
http://www.amazon.com/The-Geography-Jobs-Enrico-Moretti/dp/0...
Things get even more complicated when families come into the picture: a beach town in Morocco is not my own idea of the place I'd like to live with mine, although I certainly wouldn't mind an extended vacation there.
There are a lot of things I don't care for about my hometown in Oregon (THE WEATHER!), but I do find that I'm pretty partial to the mid-sized (which for me is something like 100K-400K, depending on various factors) university town like that where I grew up. I like being able to chat with people about programming over drinks from time to time, or talk about business, or have a variety of local businesses. On the other hand, with a family and not wanting to work for a BigCo, I'm not really interested in big cities any more.
http://www.amazon.com/The-Geography-Jobs-Enrico-Moretti/dp/0...
He talks about why things have not gone 'flat'.
And you need to make sure there's a big talent pool there, and good universities.
A few places are close to that, but it's not so easy to replicate.
This book talks about it some: https://amzn.to/2XAU3f0
And most of the places that are close have rampant NIMBYism problems of their own.