Earlier quoted context omitted.
Speaking from experience at a major infosec company, the impression I got internally was "we offer phishing tests, but we don't recommend them, because phishing succeeds 100% of the time". So I'm confused by the idea "even infosec people think training will stop this".
I disagree. There are services that regularly send fake phishing emails on a regular basis. If they click a link or fail to flag enough emails, their boss gets notified that more training is necessary. At the bank that I see this used at, the employees are far less trusting of emails and such. Training works if it's done right.
This is carefully planned phone-based spear phishing, though, and that's a lot tougher to protect against. It can be easy for a skilled con artist to gain someone's confidence over the phone, no matter how much you warn about vishing (voice phishing). I'm sure training can still help there, but attackers just keep trying again and again until they find someone it works on.