wait until one of those dev containers tries to create a symlink in the folder docker-machine shares with your host. (hint: it fails, hard, in an unfixable way)
Not sure what you're on about. I just symlinked a file on the container inside a folder that was mapped to the host and nothing bad happened. Of course the host couldn't see the content of the file, but I was able to remove the file with no errors.
If I recall correctly this is a problem with virtualbox and not docker and it's only if the symlink is made in a specific way, like how npm makes symlinks.