Car mechanic analogy
It's a bit like being trained as a BMW technician. Punter brings the car into the garage; you know how to attach and operate the diagnostic computer; and if it tells you to replace the exhaust then you know how to do that. But if the diagnostic computer says there's nothing wrong but there clearly is then you're stuffed.
IT industry certs are the same: if you want someone to build EC2 instances all day; or implement snapshot backups on a RedHat file system then getting someone with a certificate helps - and even then only if they have no other experience to prove they know it.
But if you want someone who can tell why the car starts in the cold but not when warm; and cuts out when coasting after accelerating hard then a certificate is not going to remove the need to be able to read and understand someone's CV.