> But there were benefits to knowing as, ld and ar, and there still are today.

This is trivially true. The constraint for anything you do in your life is time it takes to know something.

So the far more interesting question is: At what level do you want to solve problems – and is it likely that you need knowledge of as, ld and ar over anything else, that you could learn instead?

Knowledge of as, ld, ar, cc, etc is only needed when setting up (or modifying) your build toolchain, and in practice you can just copy-paste the build script from some other, similar project. Knowledge of these tools has never been needed.