If you’re a bog standard “dark matter developer” using high level languages or writing your typical SAAS app, you wouldn’t need it.

I turned down a job offer where the interviewer was more concerned about whether I could write a merge sort on the board (I did), than whether I could design a system. It told me a lot about the kind of people they hire.

I spent my first 12 years as a developer doing a lot of bit twiddling in C writing cross platform code with nothing but the standard library, but these days if someone asked me how to sort I would call a library function. Heck even C has a built in sort function.