Again I am not sure whose voices you are purportedly representing.
Speaking for myself, if a kid loves doing some academic activity, I would not encourage them to stop and do something else for the sake of college admissions.
If a kid instead is doing something they don’t love but because they think it looks good for college, I might encourage them to see if they can find something else they would love. And that would be true whether it was academic, non-academic, and so on.
And finally, when it comes to what sort of person any given college wants, what buckets it has to fill, or so on, I would encourage ignoring that. Be the best version of yourself, then find a great college that wants that. Don’t try to be something that isn’t the best version of yourself because some particular college might prefer that thing.
All these are consistent sentiments. And they are not telling kids they can’t love academics, if in fact that is what they love.
But if you then ask me what Harvard seems to look for, I will tell you what I believe is a good answer to that question. Not because I believe you should then do that. But because that is the question you asked.