When people looking for a smart developer as they think a developer should know everything, however the fact that a developer is not a superman.
A developer can solve your problems, but he may did a lot of search at Google or Stack Overflow lots of times.
A project may depend on lots of third party dependencies, that is a lot of work for a developer to learn or study.
I am saying we should focus on the ability which a developer can quick master new knowledge or skills, the ability a developer how to resolve the problem or an issue, but not the tech stack he or she may own, as the tech skills is always changing.
So stay hungry, stay foolish. You should always keep your skills up to date and have a lots of things to learn.