I'd definitely argue that the social isolation of not being physically in school would delay some social development, because that's largely what grade school offers imo. It's an environment for rapidly testing and experimenting with interactions between yourself and others, figuring out what works and what doesn't, resolving conflict between you and peers and older adults, forming bonds that will carry maybe into early adult years if not later ones. There's a lot of value in that, but I don't think genuinely academic learning comes until post-secondary, with the exception actually being any kind of vocational classes where you have a specific domain and framework to practice creating or doing something tangible.