I don't know her reasoning. When I am in a hurry, I generally do pillowcase (birthing) style, which is very fast. Today, I just did my third, I think, try at machine binding. This time was much better than the others. I was planning to post on my experience, so this is as good a place as any. What I learned:
1. Mitering the corners by hand before doing the rest makes it go more easilyl
2. As much as I dislike pinning, it makes the job go better. Pins about 2" apart.
3. "Double" blanket stitch is to heavy and makes the binding to stiff. Single is OK.
4. Machine binding, with all its prep is a bit better than twice as fast as my hand binding.
5. For a charity baby quilt, which one must assume will have heavy wear, machine binding is definitely stronger,
My first try at machine binding was probably 5 years ago and I swore 'never again!'. My Janome dealer said I should try it with my new machine, I still prefer the feel of hand bound for myself.