You cannot use pencils for vocals though
That's the convention, but is there's no rule that says you mustn't.
Any mic that sounds right is the right mic.

I put a Schoeps in front of Mary to record something (I think it was just a rehearsal track, but the Schoeps were new and I wanted to try them out on anything). The playback, even on a typical consumer stereo system, sounded uncannily like she was signing live in the room.

Of course, sometimes realistic isn't good enough, and then the interesting coloration you get from LDCs is what you need to make your voice sound better than it is.

Anahata