Minecraft is an awesome product and a great learning tool.
You can build pretty much anything you can imagine which means the content is what gets built by either your son or a community on a server.
A great introduction to programming through mods and scripting.
You don't need to play collaboratively. And honestly at his age I would strongly encourage he not play on open servers. You'll find just as many jerks as you would in real life.
If he wants to play with friends set up your own server.
Setting up your own server is cake. Download it, install, open the port on your firewall and done.
Only hand out the servers IP to people you approve.
Obviously you can build environments.
https://www.youtube.com/watch?v=T_OS1E6cj18
This guy built a functional 8 bit CPU in it.
Working CPU with RAM, branching, etc... (save added) - Redstone Discussion and Mechanisms - Minecraft Discussion - Minecraft Forum - Minecraft Forum
Working word processor built inside Minecraft.
Minecraft player creates word processor out of redstone - PC Gamer
One way to think of it is digital LEGO's
200+ Best Minecraft Creations
If you get into it with your son you might actually figure out a way to build guidance systems inside it.