Comment by dofm

This is to some extent a generational thing, but yes. It’s rude. If you’re not ready to politely reject numerous candidates, don’t interview them.

If you get a shitty rejection letter, you should see it as a lucky escape. A rejection burns both your bridge and theirs.

If it’s especially shitty, there is nothing stopping you publishing it as a signal to others that a recruiter or employer is wasting people's time.

Especially if you just did a coding exercise that looks suspiciously like code they might put a value on.