Zizka's Sketchbook (Nudity and Vulgarity, NSFW)

[Woden]

I've been reading that zooming can be a crutch which hinders progress? What's your take on it, do you agree?

Absolutely. In my opinion, it can mess with your ability to judge the image as a whole, to see whether the proportions of different elements are correct relative to each other.
I don't think that you should never zoom in, but you might want to do it after you've defined the basic forms of the subject of your drawing and, most importantly, you might want to zoom out regularly to take a look at the whole picture and track your progress.