That said, I don't actually mean to merely quibble over semantics and wish to clarify: Is what you meant that many tech tech companies are hoping to hire someone that just doesn't exist at all [1], rather than not existing in sufficient number?

[1] Expecting, like Dilbert's pointy-haired boss that, just because qualifications can be listed in a job description, there must exist someone who fits them all.

Assuming true, that would be limited to the silicon valley and new york area.

Try to work in tech in smaller cities and you will quickly realize that there are few employers and they can be picky.