I recently saw the job posting in Finland (Suunto, I believe) that had diving experience as an imperative requirement for an embedded software engineer role. I've applied and never heard back. HR contact that they posted also never replied. The job was closed a couple weeks after. I never even got a rejection email.

So yeah, everyone do that, that's kind of the de facto way of hiring specific people when there is a requirement to post jobs. That doesn't make it ok though.