No, I'd say they have about equal value. Consider, Google has tens of thousands of tech workers in the bay area. How many other metros could they feasibly relocate their HQ to? Even if you assume that only, say, a third of their employees decline to relocate with them, you're possibly looking at ~10,000 job openings you'd need to staff up on within a year or two to not be absolutely crippling.
> You can still do the latter in a research center that you can keep in the hub and move a lot of the other code to the periphery, which will be most of your employees.
This completely glosses over how companies work. Google doesn't have two tiers of software engineer types, where one gets more exciting stuff and better pay/benefits, while the other languishes on boring things with mediocre pay. Trying to split up the company that way, "we'll just hire crappier engineers in [cheap place] now and treat them worse because they're dumber" would be a total disaster.
> you have housing markets that are so insane that the majority of your developers will not be able to buy a house, which means they are going to leave you or demand really high wages -- wages that a company with 20K devs can't afford.
While this is absolutely a problem, and I applaud efforts to increase affordability either in the areas where tech HQ's already are, or by distributing more offices elsewhere, you're missing the obvious fact that these major tech companies already do this, and it already works. Yes, some people leave. The strongest, and probably most valuable employees largely don't, because they make enough to offset the increased cost of housing: a T6 at Google may make 400-500k/year.
Once a company reaches critical mass, it doesn't need access to VCs, and isn't able to hire superstar programmers at scale, so the quality of the average employee declines compared to what you see in startups. Now you start talking more about repeatable, workman-like code rather than brilliant groundbreaking code. You can still do the latter in a research center that you can keep in the hub and move a lot of the other code to the periphery, which will be most of your employees. After all, we are talking about HQ2 here.
At the same time, you have housing markets that are so insane that the majority of your developers will not be able to buy a house, which means they are going to leave you or demand really high wages -- wages that a company with 20K devs can't afford.
This is the inexorable logic of the market. Suppose we are not talking about people but some other scarce resource. Very expensive leather. You put that into the exotic cars but when you need to produce in high volume, you look for cheaper substitutes in order to help scale your operations. Everyone likes to think they are rockstar developers, but your typical AMZN HQ2 employee is not a rockstar, they are probably just a decent programmer (Not that there's anything wrong with that :P ). It just doesn't make sense to put HQ2 into a place where you have to pay 200K to win over the marginal employee.