Why did people used to make geocities pages back in the day? Kids like to express themselves and being able to make simple games and share them with friends is fun for them. So far it's helping him learn to read (he reads and edits his voice transcriptions before submitting), and teaching him basics like bugs, game mechanics, etc. He iterates on it and adds/ removes things. He probably did several dozen iterations over 2-3 hours.

Posting it publicly is also helping him learn about people - we talked about how no matter what some percent of people won't like it and may even say it's stupid, but that will always happen and it's still worth creating things anyway.