It’s interesting to me how different ingredients of cooking can serve specialized purposes. Arrowroot’s “fine texture allows cooking at lower temperatures and for shorter periods than other starches, making it especially suitable for such egg preparations as custards, which are adversely affected by overcooking.”
This reminds me of how different types of oils serve different purposes. Grapeseed oil is especially good for stir-frying because of its high smoke point — the point at which the oil begins to smoke, generating toxic fumes and harmful free radicals — of 420 degrees Fahrenheit. Also, because of its neutral taste, it is often used as a base in salad dressings (from http://www.marthastewart.com/268547/grapeseed-oil-101).
I imagine that different types of flour also lend themselves to different purposes.
To me one of the key marks of a skillful cook is an understanding of the unique characteristics of each ingredient and using the right ingredients for the right purposes.