There's very few humans that have enough time, energy, skills, wherewithal, and money to devote to 3+ kids to make these sorts of positive "three's company" interactions happen in the modern world. I am not saying that it's impossible, just that it's difficult and doesn't happen naturally like you're implying.

On a personal note, I never had much positive interactions with either of my siblings, certainly not as children as not now that we're in our 40s either. Lots of fighting, absolutely zero closeness or positive feelings.