As much as I want to agree with @Stamets on the basis he's a cool guy, this is an argument I can get behind.

Make the ingredient oil

As someone who can't eat butter, 99% of the time you can make this move with a neutral-tasting cooking oil. Some folks are in love with how butter changes a dish's flavor or richness, but there are many other ways to add fatty acids and glutamates to food. So it really is kind of bullshit - save time and reach for the vegetable oil.

The only exception are dishes that need the cooking fat to solidify in the fridge. Coconut oil and lard (suet too - but who has that?!) can work for those uses, but think ahead and beware of your melting points. You don't want to deliver an oily mess of food to a friend's house because it was warm out.