So in my humble opinion, sometimes an antagonist just has to be a "hurdle" for the protagonist to face. Whether that is through an evil dark lord, or whether it is through a force of nature or something else, or if it's just a person who gets in the way, that is all completely fine.
Also, I might add that in some cases, having an antagonist who isn't evil might make some antagonists more relatable, and there's a higher likelihood of this being the case if you're writing something that might have either some flavors of or just be contemporary through and through.