Hey there,
As Jon mentioned, a paper is definitely a boost (but I agree - let's keep it in perspective, it isn't a game changer). The short answer, however, is a paper does not replace leadership roles. They're two very different things and go to different key themes. Thought leadership and research capabilities are great skills to highlight but the more common definition of leadership is also critical. You have to find a balance between the academic and practical, does that make sense?
Can you do both? I don't know your constraints or bandwidth but I suggest this because these experiences wouldn't necessarily be showcased the same way in your application. For example, a great leadership experience would earn vertical real estate on your resume versus a published paper wouldn't warrant more than one line.
So if your decision is one or the other, then leadership may be the way to go if the role/organization are impactful (and if you don't have a significant leadership footprint in your application). However, if you can do both or you already have leadership positions, a paper can definitely be a differentiator.
Cheers,
Bhavik