Lots of people do this and love it. The point of doing this is to remove some of the feeling of greasiness we get in the anhydrous or non-water containing products that are made of butters, oils, and other emollients. It also stiffens the product.
I admit I've only done this once a very long time ago, so I'm only going by what I've read from readers like you and people on the Dish forum. I like my products to feel greasy, so adding these ingredients would change that skin feel.
You can use a variety of starches for this application, like corn starch, tapioca starch, Dry Flo, and Natrasorb, to name a few. The suggestions I've seen is that we can add a starch a pinch at a time while whipping our butters. I saw it suggested as up to 1/4 tsp for every ounce of butter (but remember htat we hate using volume measurements, so write down how much you used by weight!).
If you want a less greasy feeling whipped butter, consider using less greasy ingredients - for instance, hazelnut oil instead of a greasier feeling oil or mango butter instead of shea butter - and consider using something like IPM, an ester that can reduce the feeling of greasiness in our products.
Creating a whipped butter - a visual tutorial
Newbie Tuesday: Creating whipped butters - a recipe to try