It's interesting - most developers don't seem to really take certifications into account, but they still seem popular in the sysadmin/devops crowd (AWS in particular seems kind of nuts for them, not sure why).

One assumption I've made (in my 30+ certs over 20 years, all in sysadmin/tools) is that ops/sysadmin can be much more tool/feature centric. It's rather easy to test someone's ability to know cli options or know the "one way" to configure a tool.