I run IT across two schools. The primary (elementary) has over 120 Chromebooks and the high school has 27 (which will increase over the next few months). I believe it's one for every child in Years 3-6. The reason behind this is to encourage computer skills as well as the whole technology in education fad that's been going on for the last few years.
As far as Chromebooks go, they're great for this purpose; they can be managed through the Google Admin console, they're inexpensive (AUD $350ish) and they do the things that most students need (i.e. word processing and web browsing). The fact that Google Docs is also cloud-based means if the Chromebook dies or they need to use another computer - it's there.
Our accounts are also setup through head office and managed through Google so it makes sense to use a device that is designed around such an account.
From a financial and practicality sense, this makes sense for the most part. I personally prefer dealing with Windows based stuff - and I know they're trying to convince the other schools in the region to move away from typical network shares to Google Drive - but as far as this plan goes it seems mostly reasonable.
As for "a Chromebook is something you sell to people who don't know what they're doing"; yes and no. They're great and (again) inexpensive portable devices, and you can get them in a wide variety (such as ones with tablet mode). They also have good battery life.
The fact of the matter is, if it's someone who doesn't know what they're doing, they need some sort of training. Therefore, you can sit them in front of Windows, OSX or Ubuntu and give them just enough training for what they do need. One isn't inherently easier than the other (that said, I would never suggest a Mac to someone who just needs a computer for web browsing).
However, if someone knows how to use a Windows computer and you can justify the extra expense, they're better off using a Windows computer. Viruses are also an issue for Chromebooks (but mostly in the form of dodgy extensions, so less of a huge deal to remove, but they can be just as bad).