Yep, this is it. I volunteered for my school’s IT department in high school, this was basically the logic. The laptops are cheap and easy to manage/administrate. Whether or not they were Linux was a non-issue.

Edit: also, since chromeOS is basically just a browser, there wasn’t much that could break, and if something did break everything was stored in google drive anyway, so you could just factory reset the device and hand it back to the student without needing to buy any kind of higher-level support contract.