15 years ago, it was normal that, as a developer, you know how to administer a server, know how Unix works, know how to setup/debug the database. Maybe know a bit of C.
Fast forward to 2015. Lots of developers are purely frontend developers and don't know how to setup a server, or don't know how to administer the database. This is now the norm. The developers who could do all that stuff (as they should) are suddenly "full-stack developers".