When you say "astringent" it makes me think "drying out" - but that's not the case with "astringent" oils and butters? I used to think I liked drier lotions too until recently. I find they don't leave the (greasy, if you will) layer that I guess I like! But I do like them to eventually soak in. Do the astringents moisturize as well?
An astringent is actually defined as "chemical that tends to shrink or constrict body tissues, usually locally after topical medicinal application." By definition an astringent isn't necessarily a drying thing, but we do perceive moisturizing ingredients with astringent qualities as drying. These more astringent oils and butters still moisturize well, but they will give you the perception of being drier than regular oils.
Let's take something like mango butter, considered a dry or astringent butter. The tannins in the butter may make it feel astringent, and it may "shrink or constrict" your skin, but the fatty acids and phytosterols are still offering amazing moisturizing qualities, so you are still getting a nicely moisturizing creation!
If we took something like witch hazel, which contains a lot of tannins but no moisturizing fatty acids and polyphenols, you'll notice it will feel very dry and won't as moisturizing as a liquid without astringents (like aloe...and witch hazel is a light humectant, so you'll feel some light moisturizing there, but that's a post for the near future...)
So using an astringent butter or oil will be as moisturizing as a non-astringent butter or oil, but it will feel drier on your skin.