Yes, children need socialization and contact. But ALL the time?

I've seen several articles arguing that children, especially young children, need to be allowed to go back to school physically, because physical social interaction is essential for their healthy development into well-balanced adults.
I'm sure this is true, and I'm sure there are no end of studies proving this. What I am less sure about is how much difference TEMPORARY isolation makes to child development, and I have struggled to find studies that deal with this. So, while I am sure that children do need physical interaction, peer play and socialization, and that a child that never gets that will struggle to develop healthily and normally, is there a significant difference between a 3-month hiatus (which is where we are right now, in Ontario at any rate) and, say, a 6-month hiatus (which would take us to September, and the start of the regular school year)?
My educated guess is that there would not be a significant difference, and that a temporary period of isolation of this kind is unlikely to have a material effect on the mental and social development of children.
If that is the case, then the urgings of these so-called child development experts - such as the petition of over 1,000 Quebec physicians, and the statement from the Canadian Paediatric Society - is surely misplaced, and could end up causing more harm than good if it leads to a spike in COVID-19 cases, and even associated deaths.
Many people have their own little area of expertise and concern, and they are keen to get the best for their "own" people. They are essentially single-issue lobby groups. But not everyone thinks through the consequences, or looks at the big picture. I guess that is the job of the Chief Medical Officer, but unfortunately not all Chief Medical Officers are truly independent or immune to pressure from lobby groups, and I worry about what is happening here in Ontario during our rather precipitate re-opening of the economy.