It does but you have to do that from the Windows file system not the Linux one. So from Linux you are accessing /mnt/c/Users/you/somedocument and from Windows it's C:\Users\you\somedocument.
No, it's always been that way from the initial release. It's literally the only file system interopt that exists.
You're not supposed to access the Linux filesystem from Windows -- it's in a system hidden area of your profile but some people still tried to mess with it with unfortunate consequences.