I agree with being more comb than T, but you are confusing knowledge of a framework with knowledge of a technology. OOP vs functional, declarative vs imperative, actor model vs csp vs asyc/await and so on… The challenge I see is not switching from React to Vue or Svelte, but from Javascript to SQL, or from Java multithreading programming to Go coroutines or Erlang actors, or from imperative programming to understanding why stochastic gradient descent is sometimes a better solution, and why. My 2c ☺