That may be what you use it for, but that doesn't mean other people use it in that way. And it doesn't mean that's how Google represents it in their documents.

I tried to look for documentation about what Google Drive should and shouldn't be used for.

In the FAQ Google Drive said it could be used for storing any file type. There are instructions for how to backup/sync any folder on your computer to Google Drive. If you're an organization that has several people backing up folders with large numbers of files, there's nothing Google says that makes you think you shouldnt use it that way.

https://support.google.com/drive/answer/10838124?hl=en

The only thing that indicated what it shouldn't be used for was content policy page. It basically says it shouldn't be used for illegal activity and that it shouldn't be used for streaming video.

https://support.google.com/docs/answer/148505