It doesn't train them how to use real computers, but that's not on the state standards so they don't care.
Arguably, it really should be.
The reasons schools ate them up os because they're cheap and were the most readily available laptops during a shortage. I really doubt much else was on anyone's mind.
1. For a Linux user, you can already build such a system yourself quite trivially by getting an FTP account, mounting it locally with curlftpfs, and then using SVN or CVS on the mounted filesystem. From Windows or Mac, this FTP account could be accessed through built-in software.
2. It doesn't actually replace a USB drive. Most people I know e-mail files to themselves or host them somewhere online to be able to perform presentations, but they still carry a USB drive in case there are connectivity problems. This does not solve the connectivity issue.
I love web based software (minus the logins). This saves soooo much time in a teaching environment. Time that can me used for teaching ideas, approaches, rather than struggling with compatibility issues.
That said, also as a teacher and a parent, I worry that Chromebooks are making kids have no idea about the world of non-web-apps. (And file systems, etc. etc.)
I watch my kid create a poster: find an image online, copy & paste into an automatic background remover, c&p into an image editing program to remove the watermark, c&p into Canva for assembling with text etc.
Meanwhile I show her that I can do the whole thing on Pixelmator Pro (or Affinity or Photoshop) and she looks at me like I have three heads.