Of course you can skip wearing eyeshadow primer when you’re doing smoky eyes, and if you do, the world as we know it will not fall apart.
EVERYTHING WILL BE OK, PEOPLE!
But I do think that primer is usually a good idea, especially when doing smoky eyes, because primer makes your lids smoother, which, in turn, makes your eyeshadow less patchy. Primer also extends the wear time of your eye makeup. Both are good things!
Since smoky eyes usually involve a lot of layering and blending — you do a little layering, then a bit of blending, more layering, more blending — and they’re a big part of the fun, you don’t want to be working *too* hard, you know? And that’s another way in which wearing primer can help, because it makes your life easier. By enriching the color of the eyeshadows you apply on top of it, primer makes those shadows more vibrant and more intense, which in turn equals less layering!
So, on top of all the other good things primer does, it also makes smoky eyes, as well as many other eye looks, easier and faster. That way you get to spend less time on your makeup, and more time harassing your cat.
Nowadays, there are many different kinds of eyeshadow primers out there and different ways to use non-primer products as improv primers. Classic eye primers that are dedicated to priming your lids are available from most of the big brands, and my favorite one for the past few years has been NARS Pro-Prime Smudge-Proof. I think it’s seriously the best one out there now, hands down, and I’ve yet to find one better, particularly for smoky eyes.