It's kind of circumstantial: I ended up out here for a job, lived here for a while, and then started ZeroTier. It could be located in a place like Pittsburgh that has a decent talent pool but now that it's up and running and has employees it'd be a pain to move it.

That illustrates another point: ecosystems have a draw because they draw people in, and brain drain has the opposite effect. Both effects are exponential: the more people come the more people come. That's part of why interior places that have very strong university systems or major local employers with a lot of drawing power (or government labs, etc.) have been spared the worst of it.

I wasn't implying that labor arbitrage is the only cause of this depression, just that it's probably the largest single cause.