It makes sense that it would be highly dependent on comments because for one, Lemmy’s default filter is activity based so the more activity a new post has, the higher it will rank, until displaced by a newer post. The second part is that if there aren’t any comments there people might be less likely to leave comments and the post is more likely to do poorly as it’ll get bumped down by posts with higher activity. Obviously not everyone uses the activity sort feature, some sort by new, top, or scaled, but since activity is the default most will use that. Especially since it shows posts with the most discussion and activity, the ones most likely to find other people interacting on.