Too much choice. Back when I started working in code for a living (Mid 80s) you could keep a wide knowledge up to date. Not now the field is so wide you ether ending up with no depth to your stills and focus wide or go deep.

I prefer the deep route, makes you a better coder in that focused area. I explore other stuff when I get the chance, hence stuff like the F# roguelike. Big enough to test stuff but small enough to be throwaway just to learn :)