Also, the heap.
Think about it - those who don't know these things, and don't care - usually gravitate around a singular technology that lets them ignore the details. Those who do know these things, and how to use them properly, usually don't have any particular focal gravity, and are prone to be more flexible, in terms of tooling and methodology.
To me, the "Full Stack" developer is simply someone who cares about whats happening under the hood. The "millennial developers" simply don't.
We had this same issue in the 70's, 80's and 90's, but of course the tools were moderately different. Where once you had Visual Basic guys who just drag and drop things around to get things done, now you have 'npm monkeys' who, for the most part, manage dependencies and the interconnections between.
If you don't know what a stack/heap/allocator is, there is no better time to learn! The world is so rich because of these things - and if you do get an understanding of your runtime environment, well .. there's always another execution environment for your pleasure. Have at it, hacker!
(Also, its been 40 years: do you know where in the OSI model your application lives?)