If people aren't exposed to enough languages to a level of competent understanding, if not mastery, a groupthink monoculture will inevitably develop where engineers only understand JS and Python, not C, Tcl, Clojure, Erlang, Brainfuck, Haskell, Coq, Rust, etc.

The most important thing is for good engineers to understand both near-universal basic concepts and the low-level impact of data structures and algorithms (like branch mis-predictions / deep pipeline stalls, memory usage, latency, locality.)