In fact a cursory survey of the research I can publicly get access to indicates that parent-child, or teacher-child interactions are considered very essential for moral and social development and there is very little mention that I can find of inter-child interactions as a critical part. Most of the research that I can find highlights the importance of adult-child interactions. If you can point me to some studies that counteract that I'm interested.
Contra studies on the importance of inter-child interactions: * https://link.springer.com/chapter/10.1007/978-1-4684-2187-3_...
* https://www.semanticscholar.org/paper/Child-care-and-childre...
Study indicating that most of the assessment instruments supporting inter-child interactions and their importance is flawed: https://journals.sagepub.com/doi/10.1177/001440298305000310
I think you're probably underestimating how much you learned this from each other.
> but that whether this involves other children in any specific quantity is irrelevant.
Again, this very much runs contrary to the general consensus about childhood development. If you disagree, then you need to bring some facts and research to the argument.