The bond between siblings is extra-special. Sibling Day is a way of honouring that special bond. Depends on the sibling I have a younger brother where I would agree that there is a strong bond. I also have an older sister....
I have a younger brother who we rarely see. Suits both of us & our respective partners. We were never close even as children, just too different.
I'll mention that to my brother if i ever see him again after he dropped off the face of the earth about 3 years ago ...