My guess is that because Node has access to the file system and can create,update,delete files, along with all of the networking which comes out of the box, it

My guess is that because Node has access to the file system and can create,update,delete files, along with all of the networking which comes out of the box, it can do much of what an 'operating system' can from the experience of many people. It can create and manage files. The Linux kernel is still doing all the heavy lifting and i/o.