Most people making hiring decisions don't have the insight you do. To many, the presence of a certificate is a little check box they can mark off, something that makes their job easier. It doesn't help them do hiring better, it just makes it easier. Everybody talks about the PHB because the PHB is typically holding the keys to the kingdom.
The qualities you are looking for are hard to get at and evaluate. They are better indicators of long term success than a certificate, but honestly most people aren't good enough at evaluating talent to use them.
Most certifications are an oversimplification of a candidate's abilities. A candidate's skillset is a really complex space that doesn't fold down well into a simple "pass or fail" evaluation.
Congratulations on your business, and for putting in the effort to find the best fit candidates. It sounds like you are about to make some solid hires :).