Good day all!

I was watching an older Digital Tutors tutorial on modeling an interior. I had a question about specifically when he creates an iron sculpture that is part of the room's bannister. It's great, and quick how he does it, however, my only question is why not convert to polys.

My understanding is, nurbs/curves/surfaces, don't render, which is one reason we use them for rigging. However, if I was to render this cool room, I'm assuming they wouldn't render. I'm asking this question, because I have and still do, use curves/surface to build things like crown molding, complicated shapes that I can draw quicker and then loft between them. However, if I leave them as curves, am I mistaken that they won't render properly?

Should I convert them to polys?