Because they dont want to be found by some mediocre Recruiters with under market value salary. Its a waste of time and effort.
Tell you what, just for a test, offer any "unreachable senior dev" 20% higher salary and great technology stack, enough flexibility and timeoff and see what happens.
Old cvs, inactive ln etc, its because they use friends and colleagues as refferals, because it works better and they get better offers (probably have some jobs as backup option as well).
Yes, I think most would be open to good offers. The problem is that these people are very hard to find.
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